Maximum independent set on diluted triangular lattices
NASA Astrophysics Data System (ADS)
Fay, C. W., IV; Liu, J. W.; Duxbury, P. M.
2006-05-01
Core percolation and maximum independent set on random graphs have recently been characterized using the methods of statistical physics. Here we present a statistical physics study of these problems on bond diluted triangular lattices. Core percolation critical behavior is found to be consistent with the standard percolation values, though there are strong finite size effects. A transfer matrix method is developed and applied to find accurate values of the density and degeneracy of the maximum independent set on lattices of limited width but large length. An extrapolation of these results to the infinite lattice limit yields high precision results, which are tabulated. These results are compared to results found using both vertex based and edge based local probability recursion algorithms, which have proven useful in the analysis of hard computational problems, such as the satisfiability problem.
Counting independent sets using the Bethe approximation
Chertkov, Michael; Chandrasekaran, V; Gamarmik, D; Shah, D; Sin, J
2009-01-01
The authors consider the problem of counting the number of independent sets or the partition function of a hard-core model in a graph. The problem in general is computationally hard (P hard). They study the quality of the approximation provided by the Bethe free energy. Belief propagation (BP) is a message-passing algorithm can be used to compute fixed points of the Bethe approximation; however, BP is not always guarantee to converge. As the first result, they propose a simple message-passing algorithm that converges to a BP fixed pont for any grapy. They find that their algorithm converges within a multiplicative error 1 + {var_epsilon} of a fixed point in {Omicron}(n{sup 2}E{sup -4} log{sup 3}(nE{sup -1})) iterations for any bounded degree graph of n nodes. In a nutshell, the algorithm can be thought of as a modification of BP with 'time-varying' message-passing. Next, they analyze the resulting error to the number of independent sets provided by such a fixed point of the Bethe approximation. Using the recently developed loop calculus approach by Vhertkov and Chernyak, they establish that for any bounded graph with large enough girth, the error is {Omicron}(n{sup -{gamma}}) for some {gamma} > 0. As an application, they find that for random 3-regular graph, Bethe approximation of log-partition function (log of the number of independent sets) is within o(1) of corret log-partition - this is quite surprising as previous physics-based predictions were expecting an error of o(n). In sum, their results provide a systematic way to find Bethe fixed points for any graph quickly and allow for estimating error in Bethe approximation using novel combinatorial techniques.
Agreement Measure Comparisons between Two Independent Sets of Raters.
ERIC Educational Resources Information Center
Berry, Kenneth J.; Mielke, Paul W., Jr.
1997-01-01
Describes a FORTRAN software program that calculates the probability of an observed difference between agreement measures obtained from two independent sets of raters. An example illustrates the use of the DIFFER program in evaluating undergraduate essays. (Author/SLD)
Optimal BLS: Optimizing transit-signal detection for Keplerian dynamics
NASA Astrophysics Data System (ADS)
Ofir, Aviv
2015-08-01
Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. We optimize the search for transit signals for both detection and computational efficiencies by assuming that the searched systems can be described by Keplerian, and propagating the effects of different system parameters to the detection parameters. Importnantly, we mainly consider the information content of the transit signal and not any specific algorithm - and use BLS (Kovács, Zucker, & Mazeh 2002) just as a specific example.We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually.By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the transit signal parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available.
Exploiting phase transitions for fusion optimization problems
NASA Astrophysics Data System (ADS)
Svenson, Pontus
2005-05-01
Many optimization problems that arise in multi-target tracking and fusion applications are known to be NP-complete, ie, believed to have worst-case complexities that are exponential in problem size. Recently, many such NP-complete problems have been shown to display threshold phenomena: it is possible to define a parameter such that the probability of a random problem instance having a solution jumps from 1 to 0 at a specific value of the parameter. It is also found that the amount of resources needed to solve the problem instance peaks at the transition point. Among the problems found to display this behavior are graph coloring (aka clustering, relevant for multi-target tracking), satisfiability (which occurs in resource allocation and planning problem), and the travelling salesperson problem. Physicists studying these problems have found intriguing similarities to phase transitions in spin models of statistical mechanics. Many methods previously used to analyze spin glasses have been used to explain some of the properties of the behavior at the transition point. It turns out that the transition happens because the fitness landscape of the problem changes as the parameter is varied. Some algorithms have been introduced that exploit this knowledge of the structure of the fitness landscape. In this paper, we review some of the experimental and theoretical work on threshold phenomena in optimization problems and indicate how optimization problems from tracking and sensor resource allocation could be analyzed using these results.
Phase transitions in Pareto optimal complex networks.
Seoane, Luís F; Solé, Ricard
2015-09-01
The organization of interactions in complex systems can be described by networks connecting different units. These graphs are useful representations of the local and global complexity of the underlying systems. The origin of their topological structure can be diverse, resulting from different mechanisms including multiplicative processes and optimization. In spatial networks or in graphs where cost constraints are at work, as it occurs in a plethora of situations from power grids to the wiring of neurons in the brain, optimization plays an important part in shaping their organization. In this paper we study network designs resulting from a Pareto optimization process, where different simultaneous constraints are the targets of selection. We analyze three variations on a problem, finding phase transitions of different kinds. Distinct phases are associated with different arrangements of the connections, but the need of drastic topological changes does not determine the presence or the nature of the phase transitions encountered. Instead, the functions under optimization do play a determinant role. This reinforces the view that phase transitions do not arise from intrinsic properties of a system alone, but from the interplay of that system with its external constraints.
Beyond Maximum Independent Set: AN Extended Model for Point-Feature Label Placement
NASA Astrophysics Data System (ADS)
Haunert, Jan-Henrik; Wolff, Alexander
2016-06-01
Map labeling is a classical problem of cartography that has frequently been approached by combinatorial optimization. Given a set of features in the map and for each feature a set of label candidates, a common problem is to select an independent set of labels (that is, a labeling without label-label overlaps) that contains as many labels as possible and at most one label for each feature. To obtain solutions of high cartographic quality, the labels can be weighted and one can maximize the total weight (rather than the number) of the selected labels. We argue, however, that when maximizing the weight of the labeling, interdependences between labels are insufficiently addressed. Furthermore, in a maximum-weight labeling, the labels tend to be densely packed and thus the map background can be occluded too much. We propose extensions of an existing model to overcome these limitations. Since even without our extensions the problem is NP-hard, we cannot hope for an efficient exact algorithm for the problem. Therefore, we present a formalization of our model as an integer linear program (ILP). This allows us to compute optimal solutions in reasonable time, which we demonstrate for randomly generated instances.
Optimized pulse sequences for suppressing unwanted transitions in quantum systems
Schroeder, C. A.; Agarwal, G. S.
2011-01-15
We investigate the nature of the pulse sequence so that unwanted transitions in quantum systems can be inhibited optimally. For this purpose we show that the sequence of pulses proposed by Uhrig [Phys. Rev. Lett. 98, 100504 (2007)] in the context of inhibition of environmental dephasing effects is optimal. We derive exact results for inhibiting the transitions and confirm the results numerically. We posit a very significant improvement by usage of the Uhrig sequence over an equidistant sequence in decoupling a quantum system from unwanted transitions. The physics of inhibition is the destructive interference between transition amplitudes before and after each pulse.
Optimal and robust control of transition
NASA Technical Reports Server (NTRS)
Bewley, T. R.; Agarwal, R.
1996-01-01
Optimal and robust control theories are used to determine feedback control rules that effectively stabilize a linearly unstable flow in a plane channel. Wall transpiration (unsteady blowing/suction) with zero net mass flux is used as the control. Control algorithms are considered that depend both on full flowfield information and on estimates of that flowfield based on wall skin-friction measurements only. The development of these control algorithms accounts for modeling errors and measurement noise in a rigorous fashion; these disturbances are considered in both a structured (Gaussian) and unstructured ('worst case') sense. The performance of these algorithms is analyzed in terms of the eigenmodes of the resulting controlled systems, and the sensitivity of individual eigenmodes to both control and observation is quantified.
Optimizing the search for transiting planets in long time series
NASA Astrophysics Data System (ADS)
Ofir, Aviv
2014-01-01
Context. Transit surveys, both ground- and space-based, have already accumulated a large number of light curves that span several years. Aims: The search for transiting planets in these long time series is computationally intensive. We wish to optimize the search for both detection and computational efficiencies. Methods: We assume that the searched systems can be described well by Keplerian orbits. We then propagate the effects of different system parameters to the detection parameters. Results: We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ~330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually. Conclusions: By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the BLS parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available. The MATLAB code is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A138
Topology of optimally controlled quantum mechanical transition probability landscapes
Rabitz, H.; Ho, T.-S.; Hsieh, M.; Kosut, R.; Demiralp, M.
2006-07-15
An optimally controlled quantum system possesses a search landscape defined by the physical objective as a functional of the control field. This paper particularly explores the topological structure of quantum mechanical transition probability landscapes. The quantum system is assumed to be controllable and the analysis is based on the Euler-Lagrange variational equations derived from a cost function only requiring extremizing the transition probability. It is shown that the latter variational equations are automatically satisfied as a mathematical identity for control fields that either produce transition probabilities of zero or unit value. Similarly, the variational equations are shown to be inconsistent (i.e., they have no solution) for any control field that produces a transition probability different from either of these two extreme values. An upper bound is shown to exist on the norm of the functional derivative of the transition probability with respect to the control field anywhere over the landscape. The trace of the Hessian, evaluated for a control field producing a transition probability of a unit value, is shown to be bounded from below. Furthermore, the Hessian at a transition probability of unit value is shown to have an extensive null space and only a finite number of negative eigenvalues. Collectively, these findings show that (a) the transition probability landscape extrema consists of values corresponding to no control or full control, (b) approaching full control involves climbing a gentle slope with no false traps in the control space and (c) an inherent degree of robustness exists around any full control solution. Although full controllability may not exist in some applications, the analysis provides a basis to understand the evident ease of finding controls that produce excellent yields in simulations and in the laboratory.
Soil Vapor Extraction System Optimization, Transition, and Closure Guidance
Truex, Michael J.; Becker, Dave; Simon, Michelle A.; Oostrom, Martinus; Rice, Amy K.; Johnson, Christian D.
2013-02-08
Soil vapor extraction (SVE) is a prevalent remediation approach for volatile contaminants in the vadose zone. A diminishing rate of contaminant extraction over time is typically observed due to 1) diminishing contaminant mass, and/or 2) slow rates of removal for contamination in low-permeability zones. After a SVE system begins to show indications of diminishing contaminant removal rate, SVE performance needs to be evaluated to determine whether the system should be optimized, terminated, or transitioned to another technology to replace or augment SVE. This guidance specifically addresses the elements of this type of performance assessment. While not specifically presented, the approach and analyses in this guidance could also be applied at the onset of remediation selection for a site as a way to evaluate current or future impacts to groundwater from vadose zone contamination. The guidance presented here builds from existing guidance for SVE design, operation, optimization, and closure from the U.S. Environmental Protection Agency, U.S. Army Corps of Engineers, and the Air Force Center for Engineering and the Environment. The purpose of the material herein is to clarify and focus on the specific actions and decisions related to SVE optimization, transition, and/or closure.
Transition Delay in Hypersonic Boundary Layers via Optimal Perturbations
NASA Technical Reports Server (NTRS)
Paredes, Pedro; Choudhari, Meelan M.; Li, Fei
2016-01-01
The effect of nonlinear optimal streaks on disturbance growth in a Mach 6 axisymmetric flow over a 7deg half-angle cone is investigated in an e ort to expand the range of available techniques for transition control. Plane-marching parabolized stability equations are used to characterize the boundary layer instability in the presence of azimuthally periodic streaks. The streaks are observed to stabilize nominally planar Mack mode instabilities, although oblique Mack mode disturbances are destabilized. Experimentally measured transition onset in the absence of any streaks correlates with an amplification factor of N = 6 for the planar Mack modes. For high enough streak amplitudes, the transition threshold of N = 6 is not reached by the Mack mode instabilities within the length of the cone, but subharmonic first mode instabilities, which are destabilized by the presence of the streaks, reach N = 6 near the end of the cone. These results suggest a passive flow control strategy of using micro vortex generators to induce streaks that would delay transition in hypersonic boundary layers.
Rigorous location of phase transitions in hard optimization problems.
Achlioptas, Dimitris; Naor, Assaf; Peres, Yuval
2005-06-01
It is widely believed that for many optimization problems, no algorithm is substantially more efficient than exhaustive search. This means that finding optimal solutions for many practical problems is completely beyond any current or projected computational capacity. To understand the origin of this extreme 'hardness', computer scientists, mathematicians and physicists have been investigating for two decades a connection between computational complexity and phase transitions in random instances of constraint satisfaction problems. Here we present a mathematically rigorous method for locating such phase transitions. Our method works by analysing the distribution of distances between pairs of solutions as constraints are added. By identifying critical behaviour in the evolution of this distribution, we can pinpoint the threshold location for a number of problems, including the two most-studied ones: random k-SAT and random graph colouring. Our results prove that the heuristic predictions of statistical physics in this context are essentially correct. Moreover, we establish that random instances of constraint satisfaction problems have solutions well beyond the reach of any analysed algorithm. PMID:15944693
Utilizing Maximal Independent Sets as Dominating Sets in Scale-Free Networks
NASA Astrophysics Data System (ADS)
Derzsy, N.; Molnar, F., Jr.; Szymanski, B. K.; Korniss, G.
Dominating sets provide key solution to various critical problems in networked systems, such as detecting, monitoring, or controlling the behavior of nodes. Motivated by graph theory literature [Erdos, Israel J. Math. 4, 233 (1966)], we studied maximal independent sets (MIS) as dominating sets in scale-free networks. We investigated the scaling behavior of the size of MIS in artificial scale-free networks with respect to multiple topological properties (size, average degree, power-law exponent, assortativity), evaluated its resilience to network damage resulting from random failure or targeted attack [Molnar et al., Sci. Rep. 5, 8321 (2015)], and compared its efficiency to previously proposed dominating set selection strategies. We showed that, despite its small set size, MIS provides very high resilience against network damage. Using extensive numerical analysis on both synthetic and real-world (social, biological, technological) network samples, we demonstrate that our method effectively satisfies four essential requirements of dominating sets for their practical applicability on large-scale real-world systems: 1.) small set size, 2.) minimal network information required for their construction scheme, 3.) fast and easy computational implementation, and 4.) resiliency to network damage. Supported by DARPA, DTRA, and NSF.
A numerical scheme for optimal transition paths of stochastic chemical kinetic systems
Liu Di
2008-10-01
We present a new framework for finding the optimal transition paths of metastable stochastic chemical kinetic systems with large system size. The optimal transition paths are identified to be the most probable paths according to the Large Deviation Theory of stochastic processes. Dynamical equations for the optimal transition paths are derived using the variational principle. A modified Minimum Action Method (MAM) is proposed as a numerical scheme to solve the optimal transition paths. Applications to Gene Regulatory Networks such as the toggle switch model and the Lactose Operon Model in Escherichia coli are presented as numerical examples.
Optimizing chemotaxis by measuring unbound-bound transitions
NASA Astrophysics Data System (ADS)
Mortimer, Duncan; Dayan, Peter; Burrage, Kevin; Goodhill, Geoffrey J.
2010-05-01
The development of the nervous system requires nerve fibres to be guided accurately over long distances in order to make correct connections between neurons. Molecular gradients help to direct these growing fibres, by a process known as chemotaxis. However, this requires the accurate measurement of concentration differences by chemoreceptors. Here, we ask how the signals from a set of chemoreceptors interacting with a concentration gradient can best be used to determine the direction of this gradient. Prior models of chemotaxis have typically assumed that the chemoreceptors produce signals reflecting just the time-averaged binding state of those receptors. In this article, we show that in fact the optimal chemotaxis performance can be achieved when, in addition, each receptor also signals the number of unbound-to-bound transitions it experiences within the observation period. Furthermore, we show that this leads to an effective halving of the observation period required for a given level of performance. We also demonstrate that the degradation in performance observed to occur at high concentrations experimentally is likely to result not from noise intrinsic to receptor binding, but rather from noise in subsequent downstream signalling.
Optimized dynamics of state to state transitions in 2-electron quantum dot molecules
NASA Astrophysics Data System (ADS)
Sælen, L.; Nepstad, R.; Degani, I.; Hansen, J. P.
2009-11-01
We investigate optimal control strategies for state to state transitions in a model of a quantum dot molecule containing two active strongly interacting electrons. The resulting optimized electric pulses are in the THz regime and can populate combinations of states with very short transition times. The speedup compared to intuitively constructed pulses is an order of magnitude. We furthermore make use of optimized pulse control in the simulation of an experimental preparation of the molecular quantum dot system. It is shown that exclusive population of certain excited states leads to a complete suppression of spin dephasing, as predicted in Nepstad et al. [1].
A method of optimal design of single-sided linear induction motor for transit
Yoon, S.B.; Hur, J.; Hyun, D.S.
1997-09-01
An optimal design method for a single-sided linear induction motor (SLIM) for transit is described. The authors propose the method which determines the overall parameters of SLIM for transit using only the rated mechanical output. When the optimization is carried out, the slot depth is used as the initial value so that the exact slot depth is calculated iteratively from the circuit equation. The optimization problem of a SLIM design is approached by use of the sequential quadratic programming (SQP). The influence of design variables is analyzed by the rated thrust and the rated velocity respectively.
Transit telescope designs optimized for multiple object spectroscopy with fibers
NASA Technical Reports Server (NTRS)
Angel, J. R. P.
1982-01-01
Instruments to simultaneously study the spectra of many objects in the field of view of a telescope can be made using fused silica fibers. The spectrograph at the 2.3m telescope of the University of Arizona has been modified for such operation, and is used routinely to study the dynamics of galaxy clusters. Consideration has been given to how the multifiber technique can best be used to obtain spectra of the many faint objects identified by deep transit survey instruments and new space and radio telescopes. A transit survey such as that planned by McGraw et al. (1980), with CCDs at the focus of a 2m transit telescope, will identify objects down to 24th magnitude, and down to 22nd magnitude will give very complete data on variability and optical energy distribution. A telescope with much larger aperture is required for spectroscopic follow up. It is suggested that large telescopes dedicated to this type of work can be made and operated for only a fraction of the cost of a general-purpose telescope.
Advanced Nuclear Fuel Cycle Transitions: Optimization, Modeling Choices, and Disruptions
NASA Astrophysics Data System (ADS)
Carlsen, Robert W.
Many nuclear fuel cycle simulators have evolved over time to help understan the nuclear industry/ecosystem at a macroscopic level. Cyclus is one of th first fuel cycle simulators to accommodate larger-scale analysis with it liberal open-source licensing and first-class Linux support. Cyclus also ha features that uniquely enable investigating the effects of modeling choices o fuel cycle simulators and scenarios. This work is divided into thre experiments focusing on optimization, effects of modeling choices, and fue cycle uncertainty. Effective optimization techniques are developed for automatically determinin desirable facility deployment schedules with Cyclus. A novel method fo mapping optimization variables to deployment schedules is developed. Thi allows relationships between reactor types and scenario constraints to b represented implicitly in the variable definitions enabling the usage o optimizers lacking constraint support. It also prevents wasting computationa resources evaluating infeasible deployment schedules. Deployed power capacit over time and deployment of non-reactor facilities are also included a optimization variables There are many fuel cycle simulators built with different combinations o modeling choices. Comparing results between them is often difficult. Cyclus flexibility allows comparing effects of many such modeling choices. Reacto refueling cycle synchronization and inter-facility competition among othe effects are compared in four cases each using combinations of fleet of individually modeled reactors with 1-month or 3-month time steps. There are noticeable differences in results for the different cases. The larges differences occur during periods of constrained reactor fuel availability This and similar work can help improve the quality of fuel cycle analysi generally There is significant uncertainty associated deploying new nuclear technologie such as time-frames for technology availability and the cost of buildin advanced reactors
Optimal network modification for spectral radius dependent phase transitions
NASA Astrophysics Data System (ADS)
Rosen, Yonatan; Kirsch, Lior; Louzoun, Yoram
2016-09-01
The dynamics of contact processes on networks is often determined by the spectral radius of the networks adjacency matrices. A decrease of the spectral radius can prevent the outbreak of an epidemic, or impact the synchronization among systems of coupled oscillators. The spectral radius is thus tightly linked to network dynamics and function. As such, finding the minimal change in network structure necessary to reach the intended spectral radius is important theoretically and practically. Given contemporary big data resources such as large scale communication or social networks, this problem should be solved with a low runtime complexity. We introduce a novel method for the minimal decrease in weights of edges required to reach a given spectral radius. The problem is formulated as a convex optimization problem, where a global optimum is guaranteed. The method can be easily adjusted to an efficient discrete removal of edges. We introduce a variant of the method which finds optimal decrease with a focus on weights of vertices. The proposed algorithm is exceptionally scalable, solving the problem for real networks of tens of millions of edges in a short time.
The Repulsive Lattice Gas, the Independent-Set Polynomial, and the Lovász Local Lemma
NASA Astrophysics Data System (ADS)
Scott, Alexander D.; Sokal, Alan D.
2005-03-01
We elucidate the close connection between the repulsive lattice gas in equilibrium statistical mechanics and the Lovász local lemma in probabilistic combinatorics. We show that the conclusion of the Lovász local lemma holds for dependency graph G and probabilities { p x } if and only if the independent-set polynomial for G is nonvanishing in the polydisc of radii { p x }. Furthermore, we show that the usual proof of the Lovász local lemma - which provides a sufficient condition for this to occur - corresponds to a simple inductive argument for the nonvanishing of the independent-set polynomial in a polydisc, which was discovered implicitly by Shearer(98) and explicitly by Dobrushin.(37,38) We also present some refinements and extensions of both arguments, including a generalization of the Lovász local lemma that allows for ``soft'' dependencies. In addition, we prove some general properties of the partition function of a repulsive lattice gas, most of which are consequences of the alternating-sign property for the Mayer coefficients. We conclude with a brief discussion of the repulsive lattice gas on countably infinite graphs.
Phase transitions and optimal transport in stochastic roundabout traffic
NASA Astrophysics Data System (ADS)
Foulaadvand, M. Ebrahim; Maass, Philipp
2016-07-01
We study traffic in a roundabout model, where the dynamics along the interior lane of the roundabout are described by the totally asymmetric simple exclusion process (TASEP). Vehicles can enter the interior lane or exit from it via S intersecting streets with given rates, and locally modified dynamics at the junctions take into account that collisions of entering vehicles with vehicles approaching the entrance point from the interior lane should be avoided. A route matrix specifies the probabilities for vehicles to arrive from and to exit to certain intersecting streets. By subdividing the interior lane into segments between consecutive intersecting streets with effective entrance and exit rates, a classification of the stationary roundabout traffic in terms of TASEP multiphases is given, where each segment can be in either the low-density, high-density, or maximum current TASEP phase. A general methodology is developed, which allows one to calculate the multiphases and optimal throughput conditions based on a mean-field treatment. Explicit analytical results from this treatment are derived for equivalent interesting streets. The results are shown to be in good agreement with kinetic Monte Carlo simulations.
Phase transitions and optimal transport in stochastic roundabout traffic.
Foulaadvand, M Ebrahim; Maass, Philipp
2016-07-01
We study traffic in a roundabout model, where the dynamics along the interior lane of the roundabout are described by the totally asymmetric simple exclusion process (TASEP). Vehicles can enter the interior lane or exit from it via S intersecting streets with given rates, and locally modified dynamics at the junctions take into account that collisions of entering vehicles with vehicles approaching the entrance point from the interior lane should be avoided. A route matrix specifies the probabilities for vehicles to arrive from and to exit to certain intersecting streets. By subdividing the interior lane into segments between consecutive intersecting streets with effective entrance and exit rates, a classification of the stationary roundabout traffic in terms of TASEP multiphases is given, where each segment can be in either the low-density, high-density, or maximum current TASEP phase. A general methodology is developed, which allows one to calculate the multiphases and optimal throughput conditions based on a mean-field treatment. Explicit analytical results from this treatment are derived for equivalent interesting streets. The results are shown to be in good agreement with kinetic Monte Carlo simulations. PMID:27575145
Optimal Control of Markov Processes with Age-Dependent Transition Rates
Ghosh, Mrinal K. Saha, Subhamay
2012-10-15
We study optimal control of Markov processes with age-dependent transition rates. The control policy is chosen continuously over time based on the state of the process and its age. We study infinite horizon discounted cost and infinite horizon average cost problems. Our approach is via the construction of an equivalent semi-Markov decision process. We characterise the value function and optimal controls for both discounted and average cost cases.
NASA Astrophysics Data System (ADS)
Sorin, R.; Zitoun, R.; Desbordes, D.
2006-06-01
The aim of this experimental investigation is the study of Deflagration to Detonation Transition (DDT) in tubes in order to (i) reduce both run-up distance and time of transition ( L DDT and t DDT) in connection with Pulsed Detonation Engine applications and to (ii) attempt to scale L DDT with λCJ (the detonation cellular structure width). In DDT, the production of turbulence during the long flame run-up can lead to L DDT values of several meters. To shorten L DDT, an experimental set-up is designed to quickly induce highly turbulent initial flow. It consists of a double chamber terminated with a perforated plate of high Blockage Ratio (BR) positioned at the beginning of a 26 mm inner diameter tube containing a “Shchelkin spiral” of BR ≈ 0.5. The study involves stoichiometric reactive mixtures of H2, CH4, C3H8, and C2H4 with oxygen and diluted with N2 in order to obtain the same cell width λCJ≈10 mm at standard conditions. The results show that a shock-flame system propagating with nearly the isobaric speed of sound of combustion products, called the choking regime, is rapidly obtained. This experimental set-up allows a L DDT below 40 cm for the mixtures used and a ratio L DDT/λCJ ranging from 23 to 37. The transition distance seems to depend on the reduced activation energy ( E a/ RT c) and on the normalized heat of reaction ( Q/ a 0 2). The higher these quantities are, the shorter the ratio L DDT/λCJ is.
NASA Astrophysics Data System (ADS)
Hocker, David; Yan, Julia; Rabitz, Herschel
2016-05-01
Bose-Einstein condensates (BECs) offer the potential to examine quantum behavior at large length and time scales, as well as forming promising candidates for quantum technology applications. Thus, the manipulation of BECs using control fields is a topic of prime interest. We consider BECs in the mean-field model of the Gross-Pitaevskii equation (GPE), which contains linear and nonlinear features, both of which are subject to control. In this work we report successful optimal control simulations of a one-dimensional GPE by modulation of the linear and nonlinear terms to stimulate transitions into excited coherent modes. The linear and nonlinear controls are allowed to freely vary over space and time to seek their optimal forms. The determination of the excited coherent modes targeted for optimization is numerically performed through an adaptive imaginary time propagation method. Numerical simulations are performed for optimal control of mode-to-mode transitions between the ground coherent mode and the excited modes of a BEC trapped in a harmonic well. The results show greater than 99 % success for nearly all trials utilizing reasonable initial guesses for the controls, and analysis of the optimal controls reveals primarily direct transitions between initial and target modes. The success of using solely the nonlinearity term as a control opens up further research toward exploring novel control mechanisms inaccessible to linear Schrödinger-type systems.
Optimization of film synthesized rare earth transition metal permanent magnet systems
Cadieu, F.J.
1990-01-01
This report reviews work on the optimization of film synthesized rare earth transition metal permanent magnet systems. Topics include: high coercivity in Sm-Fe-Ti-V, Sm-Fe-V, and two element systems; ThMn{sub 12} type pseudobinary SmFe{sub 12 {minus} X}T{sub X}; and sputter process control for the synthesis of precisely textured RE-TM magnetic films. (JL)
Utilizing Direct Numerical Simulations of Transition and Turbulence in Design Optimization
NASA Technical Reports Server (NTRS)
Rai, Man M.
2015-01-01
Design optimization methods that use the Reynolds-averaged Navier-Stokes equations with the associated turbulence and transition models, or other model-based forms of the governing equations, may result in aerodynamic designs with actual performance levels that are noticeably different from the expected values because of the complexity of modeling turbulence/transition accurately in certain flows. Flow phenomena such as wake-blade interaction and trailing edge vortex shedding in turbines and compressors (examples of such flows) may require a computational approach that is free of transition/turbulence models, such as direct numerical simulations (DNS), for the underlying physics to be computed accurately. Here we explore the possibility of utilizing DNS data in designing a turbine blade section. The ultimate objective is to substantially reduce differences between predicted performance metrics and those obtained in reality. The redesign of a typical low-pressure turbine blade section with the goal of reducing total pressure loss in the row is provided as an example. The basic ideas presented here are of course just as applicable elsewhere in aerodynamic shape optimization as long as the computational costs are not excessive.
NASA Astrophysics Data System (ADS)
Prabowo, K.; Sumaryada, T.; Kartono, A.
2016-01-01
Simulation of predictive modeling oral drug namely Compartment Absorption and Transit (CAT) using Particle Swarm Optimization (PSO) algorithm has been performed. This research will be carried out optimization of kinetic constant value oral drug use PSO algorithm to obtain the best global transport constant values for CAT equation that can predict drug concentration in plasma. The value of drug absorption rate constant for drug atenolol 25 mg is k10, k12, k21, k13 and k31 with each value is 0.8562, 0.3736, 0.2191, 0.4334 and 1.000 have been obtained thus raising the value of the coefficient of determination of a model CAT. From the experimental data plasma drug concentrations used are Atenolol, the coefficient of determination (R2) obtained from simulations atenolol 25 mg (PSO) was 81.72% and 99.46%. Better correlation between the dependent variable as the drug concentration and explanatory variables such as mass medication, plasma volume, and rate of absorption of the drug has increased in CAT models using PSO algorithm. Based on the results of CAT models fit charts can predict drug concentration in plasma.
Explaining patterns in the school-to-work transition: An analysis using optimal matching.
Dorsett, Richard; Lucchino, Paolo
2014-12-01
This paper studies the school to work transition in the UK with the aim of achieving a richer understanding of individuals' trajectories in the five years after reaching school leaving age. By applying the technique of 'optimal matching' on data from 1991 to 2008, we group individuals' trajectories post-16, and identify a small number of distinct transition patterns. Our results suggest that while 9 out of 10 young people have generally positive experiences post-16, the remaining individuals exhibit a variety of histories that might warrant policy attention. We assess the extent to which characteristics at age 16 can predict which type of trajectory a young person will follow. Our analysis shows that, despite the apparent heterogeneity, virtually all at-risk trajectories are associated with a relatively small set of key 'risk factors': early pregnancy; low educational attainment and self-confidence; and disadvantaged family background. These characteristics are known to be strongly correlated across individuals and raise concerns about the degree of socio-economic polarisation in the transition from school to work. PMID:26047687
Excited meson radiative transitions from lattice QCD using variationally optimized operators
Shultz, Christian J.; Dudek, Jozef J.; Edwards, Robert G.
2015-06-02
We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.
Explaining patterns in the school-to-work transition: An analysis using optimal matching.
Dorsett, Richard; Lucchino, Paolo
2014-12-01
This paper studies the school to work transition in the UK with the aim of achieving a richer understanding of individuals' trajectories in the five years after reaching school leaving age. By applying the technique of 'optimal matching' on data from 1991 to 2008, we group individuals' trajectories post-16, and identify a small number of distinct transition patterns. Our results suggest that while 9 out of 10 young people have generally positive experiences post-16, the remaining individuals exhibit a variety of histories that might warrant policy attention. We assess the extent to which characteristics at age 16 can predict which type of trajectory a young person will follow. Our analysis shows that, despite the apparent heterogeneity, virtually all at-risk trajectories are associated with a relatively small set of key 'risk factors': early pregnancy; low educational attainment and self-confidence; and disadvantaged family background. These characteristics are known to be strongly correlated across individuals and raise concerns about the degree of socio-economic polarisation in the transition from school to work.
NASA Astrophysics Data System (ADS)
Espinoza, Néstor; Jordán, Andrés
2016-04-01
Very precise measurements of exoplanet transit light curves both from ground- and space-based observatories make it now possible to fit the limb-darkening coefficients in the transit-fitting procedure rather than fix them to theoretical values. This strategy has been shown to give better results, as fixing the coefficients to theoretical values can give rise to important systematic errors which directly impact the physical properties of the system derived from such light curves such as the planetary radius. However, studies of the effect of limb-darkening assumptions on the retrieved parameters have mostly focused on the widely used quadratic limb-darkening law, leaving out other proposed laws that are either simpler or better descriptions of model intensity profiles. In this work, we show that laws such as the logarithmic, square-root and three-parameter law do a better job that the quadratic and linear laws when deriving parameters from transit light curves, both in terms of bias and precision, for a wide range of situations. We therefore recommend to study which law to use on a case-by-case basis. We provide code to guide the decision of when to use each of these laws and select the optimal one in a mean-square error sense, which we note has a dependence on both stellar and transit parameters. Finally, we demonstrate that the so-called exponential law is non-physical as it typically produces negative intensities close to the limb and should therefore not be used.
ERIC Educational Resources Information Center
Field, David; And Others
1992-01-01
Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)
NASA Astrophysics Data System (ADS)
Bastidon, Noëmie; Horns, Dieter; Lindner, Axel
2016-07-01
The ALPS II experiment, Any Light Particle Search II at DESY in Hamburg, will look for sub-eV mass new fundamental bosons (e.g., axion-like particles, hidden photons, and other weakly interacting sub-eV particles) in the next years by means of a light-shining-through-wall setup. The ALPS II photosensor is a tungsten transition-edge sensor (W-TES) optimized for 1064 nm photons. This TES, operated at 80 mK, has already allowed single infrared photon detections as well as non-dispersive spectroscopy with very low background rates. The demonstrated quantum efficiency for such TES is up to 95 % (1064 nm) as has been already demonstrated by the US National Institute of Standards and Technology. A back-to-back measurement of the ALPS TES quantum efficiency using a calibrated charge-coupled device camera has lead to a first estimation of 30 %. Improvement methods are discussed.
Optimizing Transition Edge Sensors for High-Resolution X-ray Spectroscopy
Saab, Tarek; Bandler, Simon R.; Boyce, Kevin; Chervenak, James A.; Figueroa-Feliciano, Enectali; Iyomoto, Naoko; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E
2006-09-07
Transition Edge Sensors (TES) have found applications as astronomical detectors ranging from the microwave to the gamma ray energy bands. Each energy band, however, imposes a different set of requirements on the TES such as energy and timing resolution, focal plane coverage, and the mechanisms by which the signal is coupled to the detector. This paper focuses on the development of TESs optimized for the 0.1-10 keV energy range at the NASA Goddard Space Flight Center. Such detectors are suitable candidates for some of the upcoming X-ray observatories such as NeXT and Constellation-X. Ongoing efforts at producing, characterizing, and modeling such devices, as well as the latest results, are discussed.
Optimal design of water distribution networks by a discrete state transition algorithm
NASA Astrophysics Data System (ADS)
Zhou, Xiaojun; Gao, David Y.; Simpson, Angus R.
2016-04-01
In this study it is demonstrated that, with respect to model formulation, the number of linear and nonlinear equations involved in water distribution networks can be reduced to the number of closed simple loops. Regarding the optimization technique, a discrete state transition algorithm (STA) is introduced to solve several cases of water distribution networks. Firstly, the focus is on a parametric study of the 'restoration probability and risk probability' in the dynamic STA. To deal effectively with head pressure constraints, the influence is then investigated of the penalty coefficient and search enforcement on the performance of the algorithm. Based on the experience gained from training the Two-Loop network problem, a discrete STA has successfully achieved the best known solutions for the Hanoi, triple Hanoi and New York network problems.
Optimizing the structures of minimum and transition state on the free energy surface.
Yang, Sheng-Yong; Hristov, Iordan; Fleurat-Lessard, Paul; Ziegler, Tom
2005-01-13
Presented here is the application of a scheme for optimizing the structures of minima and transition states on the free energy surface (FES) for a path along a fixed reaction coordinate with the aid of ab initio molecular dynamics (AIMD) simulation. In the direction of the reaction coordinate, the values corresponding to the stationary points were optimized using the quasi-Newton method, in which the gradient of the free energy along the reaction coordinate was obtained by a constraint AIMD method, and the Bofill Hessian update scheme was used. The equilibrium values for the other directions were taken as the corresponding averages in the dynamic simulation. This scheme was applied to several elementary bimolecular addition reactions: (A) BH(3) + H(2)O --> H(2)O.BH(3); (B) BF(3) + NH(3) --> FB(3).NH(3); (C) SO(3) + NH(3) --> O(3)S.NH(3); (D) C(2)H(4) + CCl(2) --> H(4)C(2).CCl(2); (E) Ni(NH(2))(2) + PH(3) --> (NH(2))(2)Ni.PH(3); (F) W(CO)(5) + CO --> W(CO)(6). For reactions A, B, C, and F, no transition state (TS) exists on the potential energy surface (PES). However there is a TS on the FES. This stems from the curvature difference of the PES and -TDeltaS as a function of the reaction coordinate. For all reactions, it is found that the TS shifts toward the complexation product with increasing temperature because of the curvature increase of -TDeltaS. The equilibrium bond distances for the inactive coordinates perpendicular to the reaction coordinate always increase with temperature, which is due to the thermal excitation and anharmonicity of the PES.
Use of Capsule Small Bowel Transit Time to Determine the Optimal Enteroscopy Approach
Chalazan, Brandon; Gostout, Christopher J; Song, Louis M Wong Kee; Enders, Felicity T; Rajan, Elizabeth
2012-01-01
Background Capsule small bowel transit time (SBTT) is used to select the most effective enteroscopy approach when targeting capsule endoscopy (CE) findings. Aim of this study was to determine if capsule SBTT can be used to guide the choice of enteroscopy technique for reaching CE abnormalities. Methods Single center, retrospective study involving 60 patients. Data were abstracted from medical records of patients with abnormal CE who proceeded to enteroscopy which included push enteroscopy (PE) single balloon enteroscopy (SBE) and double balloon enteroscopy (DBE). Results Ninety five findings were documented on CE with presumed identification of 56 (59%) of these abnormalities by enteroscopy. Majority were angioectasias on CE (42%) and enteroscopy (59%). Optimal cutoff values for selection of enteroscopy procedure were: 0-21% SBTT for PE (80% sensitivity, 74% specificity, 83% PPV); 0 - 36% SBTT for antegrade SBE (93% sensitivity, 40% specificity, 82% PPV); 0 - 57% SBTT for antegrade DBE (75% sensitivity, 80% specificity, 75% PPV); and 74 - 100% SBTT for retrograde DBE (88% sensitivity, 78% specificity, 78% PPV). Conclusion Capsule SBTT may be used to guide the selection of enteroscopy approach. PE, antegrade SBE, antegrade DBE and retrograde DBE are optimal when abnormalities on CE are seen at ≤ 21%, ≤ 36%, ≤ 57% and ≥ 74% SBTT respectively.
NASA Astrophysics Data System (ADS)
González, L.; Hoki, K.; Kröner, D.; Leal, A. S.; Manz, J.; Ohtsuki, Y.
2000-12-01
Starting from optimal control, various series of infrared, ultrashort laser pulses with analytical shapes are designed in order to drive a preoriented molecule from its ground torsional state, which represents the coherent superposition of left and right atropisomers, towards a single enantiomer. Close analysis of the population dynamics, together with the underlying symmetry selection rules for the laser induced transitions, yields the mechanism. Namely, the molecule is driven from its ground vibrational state towards the coherent superposition of the lowest doublet of states via a doublet of excited torsional states with opposite symmetries. This pump-and-dump mechanism can be achieved by simpler series of analytical laser pulses. This decomposition of the optimal pulse into analytical subpulses allows us to design different scenarios for the selective preparation of left or right enantiomers. Exemplary this is demonstrated by quantum simulations of representative wave packets for the torsional motions of the model system, H2POSH, in the electronic ground state, based on the ab initio potential energy surface, and with ab initio dipole couplings.
NASA Astrophysics Data System (ADS)
Huhn, Oliver; Hauck, Judith; Hoppema, Mario; Rhein, Monika; Roether, Wolfgang
2010-05-01
We use a 20 year time series of chlorofluorocarbon (CFC) observations along the Prime Meridian to determine the temporal evolution of anthropogenic carbon (Cant) in the two deep boundary currents which enter the Weddell Basin in the south and leave it in the north. The Cant is inferred from transit time distributions (TTDs), with parameters (mean transit time and dispersion) adjusted to the observed mean CFC histories in these recently ventilated deep boundary currents. We optimize that "classic" TTD approach by accounting for water exchange of the boundary currents with an old but not CFC and Cant free interior reservoir. This reservoir in turn, is replenished by the boundary currents, which we parameterize as first order mixing. Furthermore, we account for the time-dependence of the CFC and Cant source water saturation. A conceptual model of an ideal saturated mixed layer and exchange with adjacent water is adjusted to observed CFC saturations in the source regions. The time-dependence for the CFC saturation appears to be much weaker than for Cant. We find a mean transit time of 14 years and an advection/dispersion ratio of 5 for the deep southern boundary current. For the northern boundary current we find a mean transit time of 8 years and a much advection/dispersion ratio of 140. The fractions directly supplied by the boundary currents are in both cases in the order of 10%, while 90% are admixed from the interior reservoirs, which are replenished with a renewal time of about 14 years. We determine Cant ~ 11 umol/kg (reference year 2006) in the deep water entering the Weddell Sea in the south (~2.1 Sv), and 12 umol/kg for the deep water leaving the Weddell Sea in the north (~2.7 Sv). These Cant estimates are, however, upper limits, considering that the Cant source water saturation is likely to be lower than that for the CFCs. Comparison with Cant intrusion estimates based on extended multiple linear regression (using potential temperature, salinity, oxygen, and
NASA Astrophysics Data System (ADS)
Gilliland, Ronald L.
Transits of the planets Mercury and especially Venus have been exciting events in the development of astronomy over the past few hundred years. Just two years ago the first transiting extra-solar planet, HD 209458b, was discovered, and subsequent studies during transit have contributed fundamental new knowledge. From the photometric light curve during transit one obtains a basic confirmation that the radial velocity detected object is indeed a planet by allowing precise determination of its mass and radius relative to these stellar quantities. From study of spectroscopic changes during transit it has been possible to probe for individual components of the transiting planets atmosphere. Planet transits are likely to become a primary tool for detection of new planets, especially other Earth-like planets with the Kepler Discovery Mission. Looking ahead, the additional aperture of the James Webb Space Space Telescope promises to allow the first possibility of studying the atmosphere of extra-solar Earth-analogue planets, perhaps even providing the first evidence of direct relevance to the search for signs of life on other planets.
ERIC Educational Resources Information Center
Morton, Stephen; Mergler, Amanda; Boman, Peter
2014-01-01
Students making the transition from high school to university often encounter many stressors and new experiences. Many students adjust successfully to university; however, some students do not, often resulting in attrition from the university and mental health issues. The primary aim of the current study was to examine the effects that optimism,…
Design and optimization of a deflagration to detonation transition (ddt) section
NASA Astrophysics Data System (ADS)
Romo, Francisco X.
Throughout the previous century, hydrocarbon-fueled engines have used and optimized the `traditional' combustion process called deflagration (subsonic combustion). An alternative form of combustion, detonation (supersonic combustion), can increase the thermal efficiency of the process by anywhere from 20 - 50%. Even though several authors have studied detonation waves since the 1890's and a plethora of papers and books have been published, it was not until 2008 that the first detonation-powered flight took place. It lasted for 10 seconds at 100 ft. altitude. Achieving detonation presents its own challenges: some fuels are not prone to detonate, severe vibrations caused by the cyclic nature of the engine and its intense noise are some of the key areas that need further research. Also, to directly achieve detonation either a high-energy, bulky, ignition system is required, or the combustion chamber must be fairly long (5 ft. or more in some cases). In the latter method, a subsonic flame front accelerates within the combustion chamber until it reaches supersonic speeds, thus detonation is attained. This is called deflagration-todetonation transition (DDT). Previous papers and experiments have shown that obstacles, such as discs with an orifice, located inside the combustion chamber can shorten the distance required to achieve detonation. This paper describes a hands-on implementation of a DDT device. Different disc geometries inside the chamber alter the wave characteristics at the exit of the tube. Although detonation was reached only when using pure oxygen, testing identified an obstacle configuration for LPG and air mixtures that increased pressure and wave speed significantly when compared to baseline or other obstacle configurations. Mixtures of LPG and air were accelerated to Mach 0.96 in the downstream frame of reference, which would indicate a transition to detonation was close. Reasons for not achieving detonation may include poor fuel and oxidizer mixing
Study of the bus dynamic coscheduling optimization method under urban rail transit line emergency.
Wang, Yun; Yan, Xuedong; Zhou, Yu; Wang, Jiaxi; Chen, Shasha
2014-01-01
As one of the most important urban commuter transportation modes, urban rail transit (URT) has been acting as a key solution for supporting mobility needs in high-density urban areas. However, in recent years, high frequency of unexpected events has caused serious service disruptions in URT system, greatly harming passenger safety and resulting in severe traffic delays. Therefore, there is an urgent need to study emergency evacuation problem in URT. In this paper, a method of bus dynamic coscheduling is proposed and two models are built based on different evacuation destinations including URT stations and surrounding bus parking spots. A dynamic coscheduling scheme for buses can be obtained by the models. In the model solution process, a new concept-the equivalent parking spot-is proposed to transform the nonlinear model into an integer linear programming (ILP) problem. A case study is conducted to verify the feasibility of models. Also, sensitivity analysis of two vital factors is carried out to analyze their effects on the total evacuation time. The results reveal that the designed capacity of buses has a negative influence on the total evacuation time, while an increase in the number of passengers has a positive effect. Finally, some significant optimizing strategies are proposed.
Optimizing Transition-Edge Sensor Design for High Count-Rate Applications
Smith, Stephen J.; Adams, Joe S.; Bandler, Simon R.; Brekosky, Regis P.; Brown, Ari-D.; Chervenak, James A.; Eckart, Megan E.; Kelley, Richard L.; Kilbourne, Caroline A.; Scott Porter, F.; Finkbeiner, Fred M.; Sadleir, John E.
2009-12-16
We are developing transition-edge sensor (TES) X-ray detectors optimized for high count-rate applications. These devices are fabricated on thick (300 {mu}m) Si substrates, resulting in a 20 times increase in thermal conductance to the heat sink compared to our conventional membrane isolated TES's. Operating a TES with higher heat sink conductance requires 4.5 times more bias current. This results in a 2.7 times increase in {beta}, the logarithmic derivative of resistance with respect to current. Noise measurements show a lower limit on the TES excess noise scales as (2{beta}){sup 1/2}, consistent with the near-equilibrium, non-linear expansion of the Ohmic Johnson noise. This is consistent with our membrane devices though the increased {beta} means the theoretical best attainable resolution is degraded by 25-35%. We have tested devices with different contact geometries between the absorber, and the TES and substrate. This allows us to investigate the loss of athermal phonons to the substrate, which can degrade the resolution. Results show a correlation between the stem contact area and a low-energy tail in the spectral response at 5.9 keV due to the athermal phonon loss. In several devices tested we demonstrate a resolution of 4.1-5.6 eV, coupled with detector time constants as fast as 44 {mu}s, representing an increase in detector response by 7 times compared to the membrane devices.
Study of the Bus Dynamic Coscheduling Optimization Method under Urban Rail Transit Line Emergency
Yan, Xuedong; Wang, Jiaxi; Chen, Shasha
2014-01-01
As one of the most important urban commuter transportation modes, urban rail transit (URT) has been acting as a key solution for supporting mobility needs in high-density urban areas. However, in recent years, high frequency of unexpected events has caused serious service disruptions in URT system, greatly harming passenger safety and resulting in severe traffic delays. Therefore, there is an urgent need to study emergency evacuation problem in URT. In this paper, a method of bus dynamic coscheduling is proposed and two models are built based on different evacuation destinations including URT stations and surrounding bus parking spots. A dynamic coscheduling scheme for buses can be obtained by the models. In the model solution process, a new concept—the equivalent parking spot—is proposed to transform the nonlinear model into an integer linear programming (ILP) problem. A case study is conducted to verify the feasibility of models. Also, sensitivity analysis of two vital factors is carried out to analyze their effects on the total evacuation time. The results reveal that the designed capacity of buses has a negative influence on the total evacuation time, while an increase in the number of passengers has a positive effect. Finally, some significant optimizing strategies are proposed. PMID:25530750
Near-optimal energy transitions for energy-state trajectories of hypersonic aircraft
NASA Astrophysics Data System (ADS)
Ardema, M. D.; Bowles, J. V.; Terjesen, E. J.; Whittaker, T.
1992-08-01
A problem of the instantaneous energy transition that occurs in energy-state approximation is considered. The transitions are modeled as a sequence of two load-factor bounded paths (either climb-dive or dive-climb). The boundary-layer equations associated with the energy-state dynamic model are analyzed to determine the precise location of the transition.
Cadieu, F.J.
1990-12-31
This report reviews work on the optimization of film synthesized rare earth transition metal permanent magnet systems. Topics include: high coercivity in Sm-Fe-Ti-V, Sm-Fe-V, and two element systems; ThMn{sub 12} type pseudobinary SmFe{sub 12 {minus} X}T{sub X}; and sputter process control for the synthesis of precisely textured RE-TM magnetic films. (JL)
Falvey, Jason R; Burke, Robert E; Malone, Daniel; Ridgeway, Kyle J; McManus, Beth M; Stevens-Lapsley, Jennifer E
2016-08-01
Hospital readmissions in older adult populations are an emerging quality indicator for acute care hospitals. Recent evidence has linked functional decline during and after hospitalization with an elevated risk of hospital readmission. However, models of care that have been developed to reduce hospital readmission rates do not adequately address functional deficits. Physical therapists, as experts in optimizing physical function, have a strong opportunity to contribute meaningfully to care transition models and demonstrate the value of physical therapy interventions in reducing readmissions. Thus, the purposes of this perspective article are: (1) to describe the need for physical therapist input during care transitions for older adults and (2) to outline strategies for expanding physical therapy participation in care transitions for older adults, with an overall goal of reducing avoidable 30-day hospital readmissions. PMID:26939601
Falvey, Jason R; Burke, Robert E; Malone, Daniel; Ridgeway, Kyle J; McManus, Beth M; Stevens-Lapsley, Jennifer E
2016-08-01
Hospital readmissions in older adult populations are an emerging quality indicator for acute care hospitals. Recent evidence has linked functional decline during and after hospitalization with an elevated risk of hospital readmission. However, models of care that have been developed to reduce hospital readmission rates do not adequately address functional deficits. Physical therapists, as experts in optimizing physical function, have a strong opportunity to contribute meaningfully to care transition models and demonstrate the value of physical therapy interventions in reducing readmissions. Thus, the purposes of this perspective article are: (1) to describe the need for physical therapist input during care transitions for older adults and (2) to outline strategies for expanding physical therapy participation in care transitions for older adults, with an overall goal of reducing avoidable 30-day hospital readmissions.
Yu, Yuqi; Wang, Jinan; Shao, Qiang E-mail: Jiye.Shi@ucb.com Zhu, Weiliang E-mail: Jiye.Shi@ucb.com; Shi, Jiye E-mail: Jiye.Shi@ucb.com
2015-03-28
The application of temperature replica exchange molecular dynamics (REMD) simulation on protein motion is limited by its huge requirement of computational resource, particularly when explicit solvent model is implemented. In the previous study, we developed a velocity-scaling optimized hybrid explicit/implicit solvent REMD method with the hope to reduce the temperature (replica) number on the premise of maintaining high sampling efficiency. In this study, we utilized this method to characterize and energetically identify the conformational transition pathway of a protein model, the N-terminal domain of calmodulin. In comparison to the standard explicit solvent REMD simulation, the hybrid REMD is much less computationally expensive but, meanwhile, gives accurate evaluation of the structural and thermodynamic properties of the conformational transition which are in well agreement with the standard REMD simulation. Therefore, the hybrid REMD could highly increase the computational efficiency and thus expand the application of REMD simulation to larger-size protein systems.
Structural and magnetic phase transitions near optimal superconductivity in BaFe2(As1-xPx)2
Hu, Ding; Lu, Xingye; Zhang, Wenliang; Luo, Huiqian; Li, Shiliang; Wang, Peipei; Chen, Genfu; Han, Fei; Banjara, Shree R.; Sapkota, A.; et al
2015-04-17
In this study, we use nuclear magnetic resonance (NMR), high-resolution x-ray and neutron scattering to study structural and magnetic phase transitions in phosphorus-doped BaFe2(As1-xPx)2. Thus, previous transport, NMR, specific heat, and magnetic penetration depth measurements have provided compelling evidence for the presence of a quantum critical point (QCP) near optimal superconductivity at x = 0.3. However, we show that the tetragonal-to-orthorhombic structural (Ts) and paramagnetic to antiferromagnetic (AF, TN) transitions in BaFe2(As1-xPx)2 are always coupled and approach to TN ≈ Ts ≥ Tc (≈ 29 K) for x = 0.29 before vanishing abruptly for x ≥ 0.3. These results suggestmore » that AF order in BaFe2(As1-xPx)2 disappears in a weakly first order fashion near optimal superconductivity, much like the electron-doped iron pnictides with an avoided QCP.« less
NASA Astrophysics Data System (ADS)
Hong, Sungryong; Calzetti, Daniela; Dickinson, Mark
2014-01-01
We present an objective method to remove the stellar continuum emission from narrow-band images to derive emission-line images. The method is based on the skewness of the pixel histogram of the residual images. Specifically, we exploit a transition in the skewness of the signal in the continuum-subtracted image, which appears when the image changes from being undersubtracted to oversubtracted. Tests on one-dimensional artificial images demonstrate that the transition identifies the optimal scaling factor μ to be used on the broad-band image IB in order to produce the optimal line-emission image IE, i.e., IE = IN-μIB, with IN the original (unsubtracted) narrow-band image. The advantage of this method is that it uses all information-bearing pixels in the final image, and not just a subset of those pixels (the latter being common in many traditional approaches to stellar continuum removal from narrow-band images). We apply our method to actual images, both from ground-based and space facilities, in particular to WFPC2 and ACS images from the Hubble Space Telescope, and we show that it is successful irrespective of the nature of the sources (point-like or extended). We also discuss the impact on the accuracy of the method of nonoptimal images, such as those containing saturated sources or nonuniform background, and present workarounds for those problems.
Length optimization of an S-shaped transition between offset optical waveguides.
Marcuse, D
1978-03-01
We derive expressions for the radiation loss of an S-shaped waveguide transition used to connect two straight integrated optics waveguides that are offset with respect to each other. It is assumed that the diffused integrated optics waveguides are produced with the help of an electron beam machine that allows beam positioning in the y direction only in discrete steps. We thus must consider staircase approximations to the desired smooth S-shaped curves. A waveguide whose axis consists of a staircase suffers radiation losses due to the quasi-periodic deformation of its axis. A second loss contribution comes from the S-shape of the waveguide axis. The sum of these loss contributions assumes a minimum that defines the optimum length of the transition waveguide.
Gerrits, Thomas; Calkins, Brice; Tomlin, Nathan; Lita, Adriana E; Migdall, Alan; Mirin, Richard; Nam, Sae Woo
2012-10-01
Typically, transition edge sensors resolve photon number of up to 10 or 20 photons, depending on the wavelength and TES design. We extend that dynamic range up to 1000 photons, while maintaining sub-shot noise detection process uncertainty of the number of detected photons and beyond that show a monotonic response up to ≈ 6 · 10(6) photons in a single light pulse. This mode of operation, which heats the sensor far beyond its transition edge into the normal conductive regime, offers a technique for connecting single-photon-counting measurements to radiant-power measurements at picowatt levels. Connecting these two usually incompatible operating regimes in a single detector offers significant potential for directly tying photon counting measurements to conventional cryogenic radiometric standards. In addition, our measurements highlight the advantages of a photon-number state source over a coherent pulse source as a tool for characterizing such a detector.
Optimization of film synthesized rare earth transition metal permanent magnet systems
Cadieu, F.J.
1992-01-01
Progress is reported in three areas: high coercivity Sm-Fe-Ti-V, Sm-Fe-Zr, and two element Sm-Fe Sm{sub 5}(Fe,T){sub 17} type crystalline phases; ThMn{sub 12} type pseudobinary SmFe{sub 12-x}T{sub x}(0{le}{times}{le}1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films. (DLC)
Campos, Daniel; Méndez, Vicenç
2015-12-01
Recent works have explored the properties of Lévy flights with resetting in one-dimensional domains and have reported the existence of phase transitions in the phase space of parameters which minimizes the mean first passage time (MFPT) through the origin [L. Kusmierz et al., Phys. Rev. Lett. 113, 220602 (2014)]. Here, we show how actually an interesting dynamics, including also phase transitions for the minimization of the MFPT, can also be obtained without invoking the use of Lévy statistics but for the simpler case of random walks with exponentially distributed flights of constant speed. We explore this dynamics both in the case of finite and infinite domains, and for different implementations of the resetting mechanism to show that different ways to introduce resetting consistently lead to a quite similar dynamics. The use of exponential flights has the strong advantage that exact solutions can be obtained easily for the MFPT through the origin, so a complete analytical characterization of the system dynamics can be provided. Furthermore, we discuss in detail how the phase transitions observed in random walks with resetting are closely related to several ideas recurrently used in the field of random search theory, in particular, to other mechanisms proposed to understand random search in space as mortal random walks or multiscale random walks. As a whole, we corroborate that one of the essential ingredients behind MFPT minimization lies in the combination of multiple movement scales (regardless of their specific origin). PMID:26764640
NASA Technical Reports Server (NTRS)
Burcham, Frank W., Jr.; Gilyard, Glenn B.; Myers, Lawrence P.
1990-01-01
Integration of propulsion and flight control systems and their optimization offers significant performance improvements. Research programs were conducted which have developed new propulsion and flight control integration concepts, implemented designs on high-performance airplanes, demonstrated these designs in flight, and measured the performance improvements. These programs, first on the YF-12 airplane, and later on the F-15, demonstrated increased thrust, reduced fuel consumption, increased engine life, and improved airplane performance; with improvements in the 5 to 10 percent range achieved with integration and with no changes to hardware. The design, software and hardware developments, and testing requirements were shown to be practical.
A self-contained, automated methodology for optimal flow control validated for transition delay
NASA Technical Reports Server (NTRS)
Joslin, Ronald D.; Gunzburger, Max D.; Nicolaides, R. A.; Erlebacher, Gordon; Hussaini, M. Yousuff
1995-01-01
This paper describes a self-contained, automated methodology for flow control along with a validation of the methodology for the problem of boundary layer instability suppression. The objective of control is to match the stress vector along a portion of the boundary to a given vector; instability suppression is achieved by choosing the given vector to be that of a steady base flow, e.g., Blasius boundary layer. Control is effected through the injection or suction of fluid through a single orifice on the boundary. The present approach couples the time-dependent Navier-Stokes system with an adjoint Navier-Stokes system and optimality conditions from which optimal states, i.e., unsteady flow fields, and control, e.g., actuators, may be determined. The results demonstrate that instability suppression can be achieved without any a priori knowledge of the disturbance, which is significant because other control techniques have required some knowledge of the flow unsteadiness such as frequencies, instability type, etc.
Optimized molecular dynamics force fields applied to the helix-coil transition of polypeptides.
Best, Robert B; Hummer, Gerhard
2009-07-01
Obtaining the correct balance of secondary structure propensities is a central priority in protein force-field development. Given that current force fields differ significantly in their alpha-helical propensities, a correction to match experimental results would be highly desirable. We have determined simple backbone energy corrections for two force fields to reproduce the fraction of helix measured in short peptides at 300 K. As validation, we show that the optimized force fields produce results in excellent agreement with nuclear magnetic resonance experiments for folded proteins and short peptides not used in the optimization. However, despite the agreement at ambient conditions, the dependence of the helix content on temperature is too weak, a problem shared with other force fields. A fit of the Lifson-Roig helix-coil theory shows that both the enthalpy and entropy of helix formation are too small: the helix extension parameter w agrees well with experiment, but its entropic and enthalpic components are both only about half the respective experimental estimates. Our structural and thermodynamic analyses point toward the physical origins of these shortcomings in current force fields, and suggest ways to address them in future force-field development.
Vortex phase transition and anisotropy behavior of optimized (Li1-x Fe x OH)FeSe single crystals
NASA Astrophysics Data System (ADS)
Yi, Xiaolei; Wang, Chunlei; Tang, Qingbin; Peng, Tao; Qiu, Yang; Xu, Junqi; Sun, Haibin; Luo, Yongsong; Yu, Benhai
2016-10-01
(Li1-x Fe x OH)FeSe single crystals have been successfully synthesized by a hydrothermal ion-exchange technique. We have carried out systematic research on the influence of the concentration of selenourea (c m) on the superconducting properties of (Li1-x Fe x OH)FeSe single crystals. The optimized specimens possess an onset superconducting transition temperature T c of up to 42 K obtained at c m = 0.8 mol l-1, and the corresponding residual resistivity ratio (RRR = ρ (300 K)/ρ (T c)) is estimated to be 11. The vortex liquid-to-glass phase transition has been discussed based on the collective pinning model. The large distance between the H g and H c2 lines, as well as the much narrower region of the pinned vortex-liquid phase, indicate a weak vortex-pinning ability in (Li1-x Fe x OH)FeSe single crystals. The big out-plane anisotropy behavior versus temperature has been explored according to the anisotropic Ginzburg-Landau theory, and the anisotropy factor Γ displays linear behavior towards temperature similar to that of SmFeAsO1-x F x superconductors.
Optimization of the transition path of the head hardening with using the genetic algorithms
NASA Astrophysics Data System (ADS)
Wróbel, Joanna; Kulawik, Adam
2016-06-01
An automated method of choice of the transition path of the head hardening in heat treatment process for the plane steel element is proposed in this communication. This method determines the points on the path of moving heat source using the genetic algorithms. The fitness function of the used algorithm is determined on the basis of effective stresses and yield point depending on the phase composition. The path of the hardening tool and also the area of the heat affected zone is determined on the basis of obtained points. A numerical model of thermal phenomena, phase transformations in the solid state and mechanical phenomena for the hardening process is implemented in order to verify the presented method. A finite element method (FEM) was used for solving the heat transfer equation and getting required temperature fields. The moving heat source is modeled with a Gaussian distribution and the water cooling is also included. The macroscopic model based on the analysis of the CCT and CHT diagrams of the medium-carbon steel is used to determine the phase transformations in the solid state. A finite element method is also used for solving the equilibrium equations giving us the stress field. The thermal and structural strains are taken into account in the constitutive relations.
Optimization of crystal nucleation close to a metastable fluid-fluid phase transition
Wedekind, Jan; Xu, Limei; Buldyrev, Sergey V.; Stanley, H. Eugene; Reguera, David; Franzese, Giancarlo
2015-01-01
The presence of a metastable fluid-fluid critical point is thought to dramatically influence the crystallization pathway, increasing the nucleation rate by many orders of magnitude over the predictions of classical nucleation theory. We use molecular dynamics simulations to study the kinetics of crystallization in the vicinity of this metastable critical point and throughout the metastable fluid-fluid phase diagram. To quantitatively understand how the fluid-fluid phase separation affects the crystal nucleation, we evaluate accurately the kinetics and reconstruct the thermodynamic free-energy landscape of crystal formation. Contrary to expectations, we find no special advantage of the proximity of the metastable critical point on the crystallization rates. However, we find that the ultrafast formation of a dense liquid phase causes the crystallization to accelerate both near the metastable critical point and almost everywhere below the fluid-fluid spinodal line. These results unveil three different scenarios for crystallization that could guide the optimization of the process in experiments PMID:26095898
NASA Astrophysics Data System (ADS)
Batzias, Dimitris F.; Pollalis, Yannis A.
2012-12-01
In several cases, a competitive market can be simulated by a game, where each company/opponent is referred to as a player. In order to accommodate the fact that each player (alone or with alliances) is working against some others' interest, the rather conservative maximin criterion is frequently used for selecting the strategy or the combination of strategies that yield the best of the worst possible outcomes for each one of the players. Under this criterion, an optimal solution is obtained when neither player finds it beneficial to alter his strategy, which means that an equilibrium has been achieved, giving also the value of the game. If conditions change as regards a player, e.g., because of either achieving an unexpected successful result in developing an innovative industrial product or obtaining higher liquidity permitting him to increase advertisement in order to acquire a larger market share, then a new equilibrium is reached. The identification of the path between the old and the new equilibrium points may prove to be valuable for investigating the robustness of the solution by means of sensitivity analysis, since uncertainty plays a critical role in this situation, where evaluation of the payoff matrix is usually based on experts' estimates. In this work, the development of a standard methodology (including 16 activity stages and 7 decision nodes) for tracing this path is presented while a numerical implementation follows to prove its functionality.
Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.
2010-01-01
Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998
NASA Astrophysics Data System (ADS)
Fischer, S. F.; Kelsch, M.; Kronmüller, H.
1999-06-01
The magnetostrictive properties of TbDyFe/Nb multilayers containing 2 at% Zr as an additive have been investigated after different annealing treatments for the (Terfenol-D near) composition of [Tb 0.27Dy 0.73] 0.27Fe 0.73. The multilayer structure has been produced by ion-beam sputtering on a sapphire substrate. After 10 min annealing of the multilayers at temperatures from 873 to 973 K the parallel magnetostriction increased from λ‖(0.8 T)=265 to 520 ppm accompanied by an increase of the magnetic phase transition temperature from TC=333 to 592 K, while the increase of the coercive fields from μ0Hc<5 to 75 mT lies distinctively below 100 mT. These properties are suitable for applications of giant magnetostrictive films in microsystems where values of λ>500 ppm, TC>500 K and μ0Hc≪100 mT are required. Establishing a nanocrystalline microstructure with grain sizes d< dc˜15 nm ( dc is the critical grain diameter) smaller than the exchange length is essential for the combination of intrinsic magnetic properties (increased λ and TC) with soft magnetic properties ( μ0Hc of a few mT) as typical for an amorphous microstructure. It is shown by microstructural XRD and TEM investigations that such a nanocrystalline microstructure can be realized by a suitable heat treatment of TbDyFe+Zr/Nb multilayers. Introducing Nb spacer layers effectively reduces grain growth for certain annealing temperatures while Zr is assumed to play a dominant role in forming nucleation centers of nanograins. In combination, both effects can be well used to optimize the magnetostrictive layer properties.
ERIC Educational Resources Information Center
Biskin, Donald S.; Rice, Deborah
The effectiveness of acceleration training with children who were in a transition period was examined. Forty-eight kindergarten children were separated into four groups on the basis of their status (Preoperational vs. Transitional) and whether or not they received three sessions of inversion-negation training. The results of the immediate and…
Abe, Daijiro; Fukuoka, Yoshiyuki; Horiuchi, Masahiro
2015-01-01
The oxygen cost of transport per unit distance (CoT; mL·kg(-1)·km(-1)) shows a U-shaped curve as a function of walking speed (v), which includes a particular walking speed minimizing the CoT, so called economical speed (ES). The CoT-v relationship in running is approximately linear. These distinctive walking and running CoT-v relationships give an intersection between U-shaped and linear CoT relationships, termed the energetically optimal transition speed (EOTS). This study investigated the effects of subtracting the standing oxygen cost for calculating the CoT and its relevant effects on the ES and EOTS at the level and gradient slopes (±5%) in eleven male trained athletes. The percent effects of subtracting the standing oxygen cost (4.8 ± 0.4 mL·kg(-1)·min(-1)) on the CoT were significantly greater as the walking speed was slower, but it was not significant at faster running speeds over 9.4 km·h(-1). The percent effect was significantly dependent on the gradient (downhill > level > uphill, P < 0.001). The net ES (level 4.09 ± 0.31, uphill 4.22 ± 0.37, and downhill 4.16 ± 0.44 km·h(-1)) was approximately 20% slower than the gross ES (level 5.15 ± 0.18, uphill 5.27 ± 0.20, and downhill 5.37 ± 0.22 km·h(-1), P < 0.001). Both net and gross ES were not significantly dependent on the gradient. In contrast, the gross EOTS was slower than the net EOTS at the level (7.49 ± 0.32 vs. 7.63 ± 0.36 km·h(-1), P = 0.003) and downhill gradients (7.78 ± 0.33 vs. 8.01 ± 0.41 km·h(-1), P < 0.001), but not at the uphill gradient (7.55 ± 0.37 vs. 7.63 ± 0.51 km·h(-1), P = 0.080). Note that those percent differences were less than 2.9%. Given these results, a subtraction of the standing oxygen cost should be carefully considered depending on the purpose of each study.
SANS study of vortex lattice structural transition in optimally doped (Ba1-x K x )Fe2As2
NASA Astrophysics Data System (ADS)
Demirdiş, S.; van der Beek, C. J.; Mühlbauer, S.; Su, Y.; Wolf, Th
2016-10-01
Small-angle neutron scattering on high quality single crystalline Ba1-x K x Fe2As2 reveals the transition from a low-field vortex solid phase with orientational order to a vortex polycrystal at high magnetic field. The vortex order-disorder transition is correlated with the second-peak feature in isothermal hysteresis loops, and is interpreted in terms of the generation of supplementary vortex solid dislocations. The sharp drop of the structure factor above the second peak field is explained by the dynamics of freezing of the vortex ensemble in the high field phase.
SANS study of vortex lattice structural transition in optimally doped (Ba1-x K x )Fe2As2.
Demirdiş, S; van der Beek, C J; Mühlbauer, S; Su, Y; Wolf, Th
2016-10-26
Small-angle neutron scattering on high quality single crystalline Ba1-x K x Fe2As2 reveals the transition from a low-field vortex solid phase with orientational order to a vortex polycrystal at high magnetic field. The vortex order-disorder transition is correlated with the second-peak feature in isothermal hysteresis loops, and is interpreted in terms of the generation of supplementary vortex solid dislocations. The sharp drop of the structure factor above the second peak field is explained by the dynamics of freezing of the vortex ensemble in the high field phase. PMID:27541966
Della Pietra, Emilia; Simonella, Francesca; Bonavida, Benjamin; Xodo, Luigi Emilio; Rapozzi, Valentina
2015-02-15
Photodynamic therapy (PDT) is a clinically approved treatment that causes a selective cytotoxic effect in cancer cells. In addition to the production of singlet oxygen and reactive oxygen species, PDT can induce the release of nitric oxide (NO) by up-regulating nitric oxide synthases (NOS). Since non-optimal PDT often causes tumor recurrence, understanding the molecular pathways involved in the photoprocess is a challenging task for scientists. The present study has examined the response of the PC3 human metastatic prostate cancer cell line following repeated low-dose pheophorbide a treatments, mimicking non-optimal PDT treatment. The analysis was focused on the NF-kB/YY1/RKIP circuitry as it is (i) dysregulated in cancer cells, (ii) modulated by NO and (iii) correlated with the epithelial to mesenchymal transition (EMT). We hypothesized that a repeated treatment of non-optimal PDT induces low levels of NO that lead to cell growth and EMT via the regulation of the above circuitry. The expressions of gene products involved in the circuitry and in EMT were analyzed by western blot. The findings demonstrate the cytoprotective role of NO following non-optimal PDT treatments that was corroborated by the use of L-NAME, an inhibitor of NOS.
Cadieu, F.J.
1992-08-01
Progress is reported in three areas: high coercivity Sm-Fe-Ti-V, Sm-Fe-Zr, and two element Sm-Fe Sm{sub 5}(Fe,T){sub 17} type crystalline phases; ThMn{sub 12} type pseudobinary SmFe{sub 12-x}T{sub x}(0{le}{times}{le}1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films. (DLC)
Graves, Barbara W; Haley, Mary Mumford
2013-01-01
The transition from intrauterine to extrauterine life is a complex adaptation. Although, in a sense, the entire time in utero is in preparation for this transition, there are many specific anatomic and physiologic changes that take place in the weeks and days leading up to labor that facilitate a healthy transition. Some, including increasing pulmonary vasculature and blood flow, are part of an ongoing process of maturation. Others, such as a reversal in the lung from secreting fluid to absorbing fluid and the secretion of pulmonary surfactant, are associated with the hormonal milieu that occurs when spontaneous labor is impending. Interventions such as elective cesarean birth or induction of labor may interfere with this preparation for birth. Postnatal interventions such as immediate clamping of the umbilical cord and oropharyngeal suction may also compromise the normal process of newborn transition. This article reviews the physiology of the fetal to newborn transition and explores interventions that may facilitate or hinder the optimal process.
NASA Astrophysics Data System (ADS)
Pahlavani, M. R.; Firoozi, B.
2015-11-01
Within a developed particle-hole approach, a systematic study of the β- transition from the ground state of the 16N nucleus to the ground and some exited states of the 16O nucleus has been carried out. The energy spectrum and the wave functions of pure configuration of the 16N and 16O nuclei are numerically obtained using the mean-field shell model with respect to the Woods-Saxon nuclear potential accompanying spin-orbit and Coulomb interaction. Considering SDI residual interaction, mixed configuration of ground and excited pnTDA and TDA states are extracted for the aforementioned nucleus. These energy spectra and corresponding eigenstates are highly correspondent to the experimental energy spectrum and eigenstates after adjusting the residual potential parameters using the Nelder-Mead (NM) algorithm. In this approach, the endpoint energy, log ft and the partial half-lives of some possible transitions are calculated. The obtained results using the optimized SDI approach are reasonably close to the available experimental data.
Integrated Network Decompositions and Dynamic Programming for Graph Optimization (INDDGO)
2012-05-31
The INDDGO software package offers a set of tools for finding exact solutions to graph optimization problems via tree decompositions and dynamic programming algorithms. Currently the framework offers serial and parallel (distributed memory) algorithms for finding tree decompositions and solving the maximum weighted independent set problem. The parallel dynamic programming algorithm is implemented on top of the MADNESS task-based runtime.
Jouany, J-P
2006-12-01
The large deficit in energy intake in relation to energy requirements during the transition and early lactation periods means that high-producing cows need energy-dense rations. High-starch diets are intensively fermented by the microbial ecosystem in the rumen, giving rise to a high production of VFAs and resulting in a drop in pH and the accumulation of lactic acid, which exacerbates the decline in pH and is considered as the major cause of rumen acidosis. This rumen dysfunction affects rumen microbes and results in less efficient digestion, thereby decreasing feed intake and exacerbating the energy deficit in the cows. The main way to limit the risk of acidosis is by diet management. Thus, animals must be progressively adapted to grain ingredients during the 3-week period before calving. Furthermore, the diet management strategy will be to privilege low-degradable starch and include enough fiber in the diet to stimulate rumination and salivation. Chemical additives can be used to prevent rumen acidosis. Rumen pH can be controlled by direct addition of chemical buffers at doses of 1-2% of DM intake. Metabolic hydrogen can be mobilized through specific metabolic pathways such as propionogenesis to compete with the synthesis of lactic acid. This can be achieved by adding propionate precursors such as aspartate, malate or fumarate. However, these additives are not economically viable, and will not easily be accepted by consumers. Probiotics, which are mainly supplied as live yeasts, have to be regarded as a solution for preventing subacute acidosis but they are not considered as an efficient cure for acute acidosis. Although the mechanisms of action of probiotics are not fully understood, this paper proposes a plausible model of their mode of action. Recently, additives based on plant extracts have been proposed as a solution for optimizing rumen functions, but further efficacy studies and safety trials are required before these additives can be marketed. The
Gravitationally induced quantum transitions
NASA Astrophysics Data System (ADS)
Landry, A.; Paranjape, M. B.
2016-06-01
In this paper, we calculate the probability for resonantly inducing transitions in quantum states due to time-dependent gravitational perturbations. Contrary to common wisdom, the probability of inducing transitions is not infinitesimally small. We consider a system of ultracold neutrons, which are organized according to the energy levels of the Schrödinger equation in the presence of the Earth's gravitational field. Transitions between energy levels are induced by an oscillating driving force of frequency ω . The driving force is created by oscillating a macroscopic mass in the neighborhood of the system of neutrons. The neutron lifetime is approximately 880 sec while the probability of transitions increases as t2. Hence, the optimal strategy is to drive the system for two lifetimes. The transition amplitude then is of the order of 1.06 ×10-5, and hence with a million ultracold neutrons, one should be able to observe transitions.
Phase Transitions in Sampling Algorithms and the Underlying Random Structures
NASA Astrophysics Data System (ADS)
Randall, Dana
Sampling algorithms based on Markov chains arise in many areas of computing, engineering and science. The idea is to perform a random walk among the elements of a large state space so that samples chosen from the stationary distribution are useful for the application. In order to get reliable results, we require the chain to be rapidly mixing, or quickly converging to equilibrium. For example, to sample independent sets in a given graph G, the so-called hard-core lattice gas model, we can start at any independent set and repeatedly add or remove a single vertex (if allowed). By defining the transition probabilities of these moves appropriately, we can ensure that the chain will converge to a use- ful distribution over the state space Ω. For instance, the Gibbs (or Boltzmann) distribution, parameterized by Λ> 0, is defined so that p(Λ) = π(I) = Λ|I| /Z, where Z = sum_{J in Ω} Λ^{|J|} is the normalizing constant known as the partition function. An interesting phenomenon occurs as Λ is varied. For small values of Λ, local Markov chains converge quickly to stationarity, while for large values, they are prohibitively slow. To see why, imagine the underlying graph G is a region of the Cartesian lattice. Large independent sets will dominate the stationary distribution π when Λ is sufficiently large, and yet it will take a very long time to move from an independent set lying mostly on the odd sublattice to one that is mostly even. This phenomenon is well known in the statistical physics community, and characterizes by a phase transition in the underlying model.
ERIC Educational Resources Information Center
Statfeld, Jenna L.
2011-01-01
Post-school transition is the movement of a child with disabilities from school to activities that occur after the completion of school. This paper provides information about: (1) post-school transition; (2) transition plan; (3) transition services; (4) transition planning; (5) vocational rehabilitation services; (6) services that are available…
Parallel Algorithms for Graph Optimization using Tree Decompositions
Weerapurage, Dinesh P; Sullivan, Blair D; Groer, Christopher S
2013-01-01
Although many NP-hard graph optimization problems can be solved in polynomial time on graphs of bounded tree-width, the adoption of these techniques into mainstream scientific computation has been limited due to the high memory requirements of required dynamic programming tables and excessive running times of sequential implementations. This work addresses both challenges by proposing a set of new parallel algorithms for all steps of a tree-decomposition based approach to solve maximum weighted independent set. A hybrid OpenMP/MPI implementation includes a highly scalable parallel dynamic programming algorithm leveraging the MADNESS task-based runtime, and computational results demonstrate scaling. This work enables a significant expansion of the scale of graphs on which exact solutions to maximum weighted independent set can be obtained, and forms a framework for solving additional graph optimization problems with similar techniques.
Parallel Algorithms for Graph Optimization using Tree Decompositions
Sullivan, Blair D; Weerapurage, Dinesh P; Groer, Christopher S
2012-06-01
Although many $\\cal{NP}$-hard graph optimization problems can be solved in polynomial time on graphs of bounded tree-width, the adoption of these techniques into mainstream scientific computation has been limited due to the high memory requirements of the necessary dynamic programming tables and excessive runtimes of sequential implementations. This work addresses both challenges by proposing a set of new parallel algorithms for all steps of a tree decomposition-based approach to solve the maximum weighted independent set problem. A hybrid OpenMP/MPI implementation includes a highly scalable parallel dynamic programming algorithm leveraging the MADNESS task-based runtime, and computational results demonstrate scaling. This work enables a significant expansion of the scale of graphs on which exact solutions to maximum weighted independent set can be obtained, and forms a framework for solving additional graph optimization problems with similar techniques.
Hu, Ding; Lu, Xingye; Zhang, Wenliang; Luo, Huiqian; Li, Shiliang; Wang, Peipei; Chen, Genfu; Han, Fei; Banjara, Shree R.; Sapkota, A.; Kreyssig, A.; Goldman, A. I.; Yamani, Z.; Niedermayer, Christof; Skoulatos, Markos; Georgii, Robert; Keller, T.; Wang, Pengshuai; Yu, Weiqiang; Dai, Pengcheng
2015-04-17
In this study, we use nuclear magnetic resonance (NMR), high-resolution x-ray and neutron scattering to study structural and magnetic phase transitions in phosphorus-doped BaFe_{2}(As_{1-x}P_{x})_{2}. Thus, previous transport, NMR, specific heat, and magnetic penetration depth measurements have provided compelling evidence for the presence of a quantum critical point (QCP) near optimal superconductivity at x = 0.3. However, we show that the tetragonal-to-orthorhombic structural (T_{s}) and paramagnetic to antiferromagnetic (AF, T_{N}) transitions in BaFe_{2}(As_{1-x}P_{x})_{2} are always coupled and approach to T_{N} ≈ T_{s} ≥ T_{c} (≈ 29 K) for x = 0.29 before vanishing abruptly for x ≥ 0.3. These results suggest that AF order in BaFe_{2}(As_{1-x}P_{x})_{2} disappears in a weakly first order fashion near optimal superconductivity, much like the electron-doped iron pnictides with an avoided QCP.
NASA Astrophysics Data System (ADS)
Smith, E. A.; Leung, H. W.-Y.; Elsner, J. B.; Mehta, A. V.; Tripoli, G. J.; Casella, D.; Dietrich, S.; Mugnai, A.; Panegrossi, G.; Sanò, P.
2013-05-01
In the first two parts of this study we have presented a performance analysis of our new Cloud Dynamics and Radiation Database (CDRD) satellite precipitation retrieval algorithm on various convective and stratiform rainfall case studies verified with precision radar ground truth data, and an exposition of the algorithm's detailed design in conjunction with a proof-of-concept analysis vis-à-vis its theoretical underpinnings. In this third part of the study, we present the underlying analysis used to identify what we refer to as the optimal metrological and geophysical tags, which are the optimally effective atmospheric and geographic parameters that are used to refine the selection of candidate microphysical profiles used for the Bayesian retrieval. These tags enable extending beyond the conventional Cloud Radiation Database (CRD) algorithm by invoking meteorological-geophysical guidance, drawn from a simulated database, which affect and are in congruence with the observed precipitation states. This is guidance beyond the restrictive control provided by only simulated radiative transfer equation (RTE) model-derived database brightness temperature (TB) vector proximity information in seeking to relate physically consistent precipitation profile solutions to individual satellite-observed TB vectors. The first two parts of the study have rigorously demonstrated that the optimal tags effectively mitigate against solution ambiguity, where use of only a CRD framework (TB guidance only) leads to pervasive non-uniqueness problems in finding rainfall solutions. Alternatively, a CDRD framework (TB + tag guidance) mitigates against non-uniqueness problems through improved constraints. It remains to show how these optimal tags are identified. By use of three statistical analysis procedures applied to a database from 120 North American atmospheric simulations of precipitating storms (independent of the 60 simulations for the European-Mediterranean basin region used in the Parts
NASA Astrophysics Data System (ADS)
Haswell, Carole A.
2010-07-01
1. Our solar system from afar; 2. Exoplanet discoveries by the transit method; 3. What the transit lightcurve tells us; 4. The transiting exoplanet population; 5. Transmission spectroscopy and Rossiter-McLaughlin effect; 6. Secondary eclipses and phase variations; 7. Transit timing variations and orbital dynamics; 8. Brave new worlds: the future; Index.
Martens, Koen; Aetukuri, Nagaphani; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.
2014-02-24
Key to the growth of epitaxial, atomically thin films is the preparation of the substrates on which they are deposited. Here, we report the growth of atomically smooth, ultrathin films of VO{sub 2} (001), only ∼2 nm thick, which exhibit pronounced metal-insulator transitions, with a change in resistivity of ∼500 times, at a temperature that is close to that of films five times thicker. These films were prepared by pulsed laser deposition on single crystalline TiO{sub 2}(001) substrates that were treated by dipping in acetone, HCl and HF in successive order, followed by an anneal at 700–750 °C in flowing oxygen. This pretreatment removes surface contaminants, TiO{sub 2} defects, and provides a terraced, atomically smooth surface.
Pareto optimal pairwise sequence alignment.
DeRonne, Kevin W; Karypis, George
2013-01-01
Sequence alignment using evolutionary profiles is a commonly employed tool when investigating a protein. Many profile-profile scoring functions have been developed for use in such alignments, but there has not yet been a comprehensive study of Pareto optimal pairwise alignments for combining multiple such functions. We show that the problem of generating Pareto optimal pairwise alignments has an optimal substructure property, and develop an efficient algorithm for generating Pareto optimal frontiers of pairwise alignments. All possible sets of two, three, and four profile scoring functions are used from a pool of 11 functions and applied to 588 pairs of proteins in the ce_ref data set. The performance of the best objective combinations on ce_ref is also evaluated on an independent set of 913 protein pairs extracted from the BAliBASE RV11 data set. Our dynamic-programming-based heuristic approach produces approximated Pareto optimal frontiers of pairwise alignments that contain comparable alignments to those on the exact frontier, but on average in less than 1/58th the time in the case of four objectives. Our results show that the Pareto frontiers contain alignments whose quality is better than the alignments obtained by single objectives. However, the task of identifying a single high-quality alignment among those in the Pareto frontier remains challenging.
Transition States and transition state analogue interactions with enzymes.
Schramm, Vern L
2015-04-21
evolved enzymatic geometry to form the transition state. Evolution to efficient catalysis optimized this geometry and its stabilization by a transition state mimic results in tight binding. Release rates of transition state analogues are orders of magnitude slower than product release in normal catalytic function. During catalysis, product release is facilitated by altered chemistry. Compared to the weak associations found in Michaelis complexes, transition state analogues involve strong interactions related to those in the transition state. Optimum binding of transition state analogues occurs when the complex retains the system motions intrinsic to transition state formation. Conserved dynamic motion retains the entropic components of inhibitor complexes, improving the thermodynamics of analogue binding.
ERIC Educational Resources Information Center
Naylor, Mary; Keating, Stacen A.
2008-01-01
Transitional care encompasses a broad range of services and environments designed to promote the safe and timely passage of patients between levels of health care and across care settings. High-quality transitional care is especially important for older adults with multiple chronic conditions and complex therapeutic regimens, as well as for their…
NASA Technical Reports Server (NTRS)
1992-01-01
This report describes NASA's metric transition in terms of seven major program elements. Six are technical areas involving research, technology development, and operations; they are managed by specific Program Offices at NASA Headquarters. The final program element, Institutional Management, covers both NASA-wide functional management under control of NASA Headquarters and metric capability development at the individual NASA Field Installations. This area addresses issues common to all NASA program elements, including: Federal, state, and local coordination; standards; private industry initiatives; public-awareness initiatives; and employee training. The concluding section identifies current barriers and impediments to metric transition; NASA has no specific recommendations for consideration by the Congress.
Four-body trajectory optimization
NASA Technical Reports Server (NTRS)
Pu, C. L.; Edelbaum, T. N.
1974-01-01
A comprehensive optimization program has been developed for computing fuel-optimal trajectories between the earth and a point in the sun-earth-moon system. It presents methods for generating fuel optimal two-impulse trajectories which may originate at the earth or a point in space and fuel optimal three-impulse trajectories between two points in space. The extrapolation of the state vector and the computation of the state transition matrix are accomplished by the Stumpff-Weiss method. The cost and constraint gradients are computed analytically in terms of the terminal state and the state transition matrix. The 4-body Lambert problem is solved by using the Newton-Raphson method. An accelerated gradient projection method is used to optimize a 2-impulse trajectory with terminal constraint. The Davidon's Variance Method is used both in the accelerated gradient projection method and the outer loop of a 3-impulse trajectory optimization problem.
Models for transition clinics.
Carrizosa, Jaime; An, Isabelle; Appleton, Richard; Camfield, Peter; Von Moers, Arpad
2014-08-01
Transition is a purposeful, planned process that addresses the medical, psychosocial, educational, and vocational needs of adolescents and young adults with chronic medical conditions, as they advance from a pediatric and family-centered to an adult, individual focused health care provider. This article describes some of the models for transition clinics or services for epilepsy in five countries (Canada, France, Colombia, Germany, and the United Kingdom). These models include joint adult and pediatric clinics, algorithm-driven service, and a check list system in the context of pediatric care. Evaluation of these models is limited, and it is not possible to choose an optimal program. The attitude and motivation of health care providers may be the most important elements. PMID:25209087
Research in bus and rail transit operations
Chatterjee, A.; Wegmann, F.J.; Ceder, A.; Levinson, H.S.; Hollander, A.
1989-01-01
The 10 papers in the report deal with the following areas: Private Sector Involvement in Sponsoring Sunday Bus Service; Optimal Design of Transit Short-Turn Trips; New York City's Unfranchised Buses: Case Study in Deregulation; Critical Factors in Planning Multimodal Passenger Terminals; Use of Travelers' Attitudes in Rail Service Design; Driven, Attended, and Fully Automated Transit; Qualitative Comparison; Impact on Transit Patronage of Cessation or Inauguration of Rail Service; Use of Productivity Factors in Estimating LRT Operating Costs; Simulation Study To Evaluate Spare Ratios in Bus Transit Systems; Statistical Evaluation of Spare Ratio in Transit Rolling Stock.
Mattei, Jean-François; Troit, Virginie
2016-02-01
In two centuries, modern humanitarian action has experienced several fractures often linked to crises. Although its professionalism and intervention force remain indisputable, it faces, since the 2000s, a new context that limits its ability to act and confronts it with new dilemmas, even though it must deal with needs for aid of unprecedented scale. These difficulties reveal a humanitarian transition period that was not anticipated. This transition period reflects the change from a dominant paradigm of North-South solidarity of Western origin to a much more complex model. This article provides a summary of the current mutations that are dominated by the States' assertion of sovereignty. Among the possible solutions, it argues for an ethical approach and a better integration of the research carried out in the Global South, prerequisites for building a true partnership and placing the victims at the heart of the operations which involve them. PMID:26936180
ERIC Educational Resources Information Center
Gallick, Barb; Lee, Lisa
2010-01-01
Adults often find themselves transitioning from one activity to another in a short time span. Most of the time, they do not feel they have a lot of control over their schedules, but wish that they could carve out extended time to relax and focus on one project. Picture a group of children in the block area who have spent 15 or 20 minutes building…
NASA Technical Reports Server (NTRS)
Laird, Philip
1992-01-01
We distinguish static and dynamic optimization of programs: whereas static optimization modifies a program before runtime and is based only on its syntactical structure, dynamic optimization is based on the statistical properties of the input source and examples of program execution. Explanation-based generalization is a commonly used dynamic optimization method, but its effectiveness as a speedup-learning method is limited, in part because it fails to separate the learning process from the program transformation process. This paper describes a dynamic optimization technique called a learn-optimize cycle that first uses a learning element to uncover predictable patterns in the program execution and then uses an optimization algorithm to map these patterns into beneficial transformations. The technique has been used successfully for dynamic optimization of pure Prolog.
Ultramaneuverable steering control algorithms for terrain transitions
NASA Astrophysics Data System (ADS)
Torrie, Mel W.; Koch, Ralf; Bahl, Vikas; Cripps, Don
1999-07-01
The Center for Self-Organizing and Intelligent Systems has built several vehicles with ultra-maneuverable steering capability. Each drive wheel on the vehicle can be independently set at any angle with respect to the vehicle body and the vehicles can rotate or translate in any direction. The vehicles are expected to operate on a wide range of terrain surfaces and problems arise in effectively controlling changes in wheel steering angles as the vehicle transitions from one extreme running surface to another. Controllers developed for smooth surfaces may not perform well on rough or 'sticky' surfaces and vice versa. The approach presented involves the development of a model of the steering motor with the static and viscous friction of the steering motor load included. The model parameters are then identified through a series of environmental tests using a vehicle wheel assembly and the model thus obtained is used for control law development. Four different robust controllers were developed and evaluated through simulation and vehicle testing. The findings of this development will be presented.
NASA Astrophysics Data System (ADS)
Varma, Shikha
We have studied thin (1-7 monolayer) overlayers of Hg on Ag(100) and Cu(100) using angle-resolved photoemission and low energy electron diffraction. We have investigated the electronic states of well ordered, disordered and the liquid overlayers of mercury. We show that the electronic structure of the well ordered overlayers is very different than that of the disordered and the liquid overlayers. The well ordered overlayers of Hg on Ag(100) exhibit a new electronic state which is absent for the disordered overlayers of mercury as well as for gaseous mercury. We will argue that this new Hg state is a result of the interaction among the Hg-Hg atoms, when adsorbed on Ag(100). The strain among adlayer atoms also plays a crucial role in the development of the new electronic state. We have used the synchrotron radiation to study the partial cross-section and the branching ratio of the 5d electronic state of Hg. We have measured the partial cross-section and branching ratio of the well-ordered, disordered and liquid overlayers of mercury on Ag(100) and Cu(100). We have observed resonances in the photoemission intensities of the mercury 5d orbitals for thin films of mercury for incident photon energies near the 5p _{3/2}, 4f_{7/2 } and 4f_{5/2} thresholds. The results indicate that interband transitions from the 5p and 4f levels to the 5d orbitals can occur for a thin overlayer of mercury, as a result of final state 5f contributions, though such interband transitions are forbidden for the free isolated Hg atom. These resonances are attributed to the formation of a solid state band structure incorporating new itinerant mercury electronic state. These resonances are absent when the mercury film is disordered or melted. We have measured the branching ratio of the 5d orbital for thin mercury overlayers in the photon energy range between 26 to 105 eV. The branching ratios deviate from the nonrelativistic statistical value of 1.5, reaching values of 8.0. These results indicate
Edge orientation for optimizing controllability of complex networks
NASA Astrophysics Data System (ADS)
Xiao, Yan-Dong; Lao, Song-Yang; Hou, Lv-Lin; Bai, Liang
2014-10-01
Recently, as the controllability of complex networks attracts much attention, how to design and optimize the controllability of networks has become a common and urgent problem in the field of controlling complex networks. Previous work focused on the structural perturbation and neglected the role of edge direction to optimize the network controllability. In a recent work [Phys. Rev. Lett. 103, 228702 (2009), 10.1103/PhysRevLett.103.228702], the authors proposed a simple method to enhance the synchronizability of networks by assignment of link direction while keeping network topology unchanged. However, the controllability is fundamentally different from synchronization. In this work, we systematically propose the definition of assigning direction to optimize controllability, which is called the edge orientation for optimal controllability problem (EOOC). To solve the EOOC problem, we construct a switching network and transfer the EOOC problem to find the maximum independent set of the switching network. We prove that the principle of our optimization method meets the sense of unambiguity and optimum simultaneously. Furthermore, the relationship between the degree-degree correlations and EOOC are investigated by experiments. The results show that the disassortativity pattern could weaken the orientation for optimal controllability, while the assortativity pattern has no correlation with EOOC. All the experimental results of this work verify that the network structure determines the network controllability and the optimization effects.
Edge orientation for optimizing controllability of complex networks.
Xiao, Yan-Dong; Lao, Song-Yang; Hou, Lv-Lin; Bai, Liang
2014-10-01
Recently, as the controllability of complex networks attracts much attention, how to design and optimize the controllability of networks has become a common and urgent problem in the field of controlling complex networks. Previous work focused on the structural perturbation and neglected the role of edge direction to optimize the network controllability. In a recent work [Phys. Rev. Lett. 103, 228702 (2009)], the authors proposed a simple method to enhance the synchronizability of networks by assignment of link direction while keeping network topology unchanged. However, the controllability is fundamentally different from synchronization. In this work, we systematically propose the definition of assigning direction to optimize controllability, which is called the edge orientation for optimal controllability problem (EOOC). To solve the EOOC problem, we construct a switching network and transfer the EOOC problem to find the maximum independent set of the switching network. We prove that the principle of our optimization method meets the sense of unambiguity and optimum simultaneously. Furthermore, the relationship between the degree-degree correlations and EOOC are investigated by experiments. The results show that the disassortativity pattern could weaken the orientation for optimal controllability, while the assortativity pattern has no correlation with EOOC. All the experimental results of this work verify that the network structure determines the network controllability and the optimization effects. PMID:25375546
Transitions: A Personal Perspective.
ERIC Educational Resources Information Center
Wood, Ann Stace
1995-01-01
Distinguishes between unchosen transitions (children maturing and leaving, parents aging, companies downsizing) and chosen ones (moving, divorce, marriage, career changes). Describes the steps one goes through: uneasiness, renewed energy, complaining, exploration, partial transition, and the completed transition. (JOW)
TRADES: TRAnsits and Dynamics of Exoplanetary Systems
NASA Astrophysics Data System (ADS)
Borsato, Luca
2016-01-01
TRADES (TRAnsits and Dynamics of Exoplanetary Systems) simultaneously fits observed radial velocities and transit times data to determine the orbital parameters of exoplanetary systems from observational data. It uses a dynamical simulator for N-body systems that also fits the available data during the orbital integration and determines the best combination of the orbital parameters using grid search, χ2 minimization, genetic algorithms, particle swarm optimization, and bootstrap analysis.
Measurement-assisted Landau-Zener transitions
NASA Astrophysics Data System (ADS)
Pechen, Alexander; Trushechkin, Anton
2015-05-01
Nonselective quantum measurements, i.e., measurements without reading the results, are often considered as a resource for manipulating quantum systems. In this work, we investigate optimal acceleration of the Landau-Zener (LZ) transitions by nonselective quantum measurements. We use the measurements of a population of a diabatic state of the LZ system at certain time instants as control and find the optimal time instants which maximize the LZ transition. We find surprising nonmonotonic behavior of the maximal transition probability with increase of the coupling parameter when the number of measurements is large. This transition probability gives an optimal approximation to the fundamental quantum Zeno effect (which corresponds to continuous measurements) by a fixed number of discrete measurements. The difficulty for the analysis is that the transition probability as a function of time instants has a huge number of local maxima. We resolve this problem both analytically by asymptotic analysis and numerically by the development of efficient algorithms mainly based on the dynamic programming. The proposed numerical methods can be applied, besides this problem, to a wide class of measurement-based optimal control problems.
Carver, Charles S; Scheier, Michael F
2014-06-01
Optimism is a cognitive construct (expectancies regarding future outcomes) that also relates to motivation: optimistic people exert effort, whereas pessimistic people disengage from effort. Study of optimism began largely in health contexts, finding positive associations between optimism and markers of better psychological and physical health. Physical health effects likely occur through differences in both health-promoting behaviors and physiological concomitants of coping. Recently, the scientific study of optimism has extended to the realm of social relations: new evidence indicates that optimists have better social connections, partly because they work harder at them. In this review, we examine the myriad ways this trait can benefit an individual, and our current understanding of the biological basis of optimism.
OPTIMIZING THROUGH CO-EVOLUTIONARY AVALANCHES
S. BOETTCHER; A. PERCUS
2000-08-01
We explore a new general-purpose heuristic for finding high-quality solutions to hard optimization problems. The method, called extremal optimization, is inspired by ''self-organized critically,'' a concept introduced to describe emergent complexity in many physical systems. In contrast to Genetic Algorithms which operate on an entire ''gene-pool'' of possible solutions, extremal optimization successively replaces extremely undesirable elements of a sub-optimal solution with new, random ones. Large fluctuations, called ''avalanches,'' ensue that efficiently explore many local optima. Drawing upon models used to simulate far-from-equilibrium dynamics, extremal optimization complements approximation methods inspired by equilibrium statistical physics, such as simulated annealing. With only one adjustable parameter, its performance has proved competitive with more elaborate methods, especially near phase transitions. Those phase transitions are found in the parameter space of most optimization problems, and have recently been conjectured to be the origin of some of the hardest instances in computational complexity. We will demonstrate how extremal optimization can be implemented for a variety of combinatorial optimization problems. We believe that extremal optimization will be a useful tool in the investigation of phase transitions in combinatorial optimization problems, hence valuable in elucidating the origin of computational complexity.
On the Bellman's principle of optimality
NASA Astrophysics Data System (ADS)
Gross, Eitan
2016-11-01
Bellman's equation is widely used in solving stochastic optimal control problems in a variety of applications including investment planning, scheduling problems and routing problems. Building on Markov decision processes for stationary policies, we present a new proof for Bellman's equation of optimality. Our proof rests its case on the availability of an explicit model of the environment that embodies transition probabilities and associated costs.
NASA Technical Reports Server (NTRS)
Macready, William; Wolpert, David
2005-01-01
We demonstrate a new framework for analyzing and controlling distributed systems, by solving constrained optimization problems with an algorithm based on that framework. The framework is ar. information-theoretic extension of conventional full-rationality game theory to allow bounded rational agents. The associated optimization algorithm is a game in which agents control the variables of the optimization problem. They do this by jointly minimizing a Lagrangian of (the probability distribution of) their joint state. The updating of the Lagrange parameters in that Lagrangian is a form of automated annealing, one that focuses the multi-agent system on the optimal pure strategy. We present computer experiments for the k-sat constraint satisfaction problem and for unconstrained minimization of NK functions.
NASA Astrophysics Data System (ADS)
Bakhtavar, E.
2015-09-01
In this study, transition from open pit to block caving has been considered as a challenging problem. For this purpose, the linear integer programing code of Matlab was initially developed on the basis of the binary integer model proposed by Bakhtavar et al (2012). Then a program based on graphical user interface (GUI) was set up and named "Op-Ug TD Optimizer". It is a beneficial tool for simple application of the model in all situations where open pit is considered together with block caving method for mining an ore deposit. Finally, Op-Ug TD Optimizer has been explained step by step through solving the transition from open pit to block caving problem of a case ore deposit. W pracy tej rozważano skomplikowane zagadnienie przejścia od wybierania odkrywkowego do komorowego. W tym celu opracowano kod programowania liniowego w środowisku MATLAB w oparciu o model liczb binarnych zaproponowany przez Bakhtavara (2012). Następnie opracowano program z wykorzystujący graficzny interfejs użytkownika o nazwie Optymalizator Op-Ug TD. Jest to niezwykle cenne narzędzie umożliwiające stosowanie modelu dla wszystkich warunków w sytuacjach gdy rozważamy prowadzenie wydobycia metodą odkrywkową oraz wydobycie komorowe przy eksploatacji złóż rud żelaza. W końcowej części pracy podano szczegółową instrukcję stosowanie programu Optymalizator na przedstawionym przykładzie przejścia od wydobycia rud żelaza metodami odkrywkowymi poprzez wydobycie komorami.
Optimal Protocols and Optimal Transport in Stochastic Thermodynamics
NASA Astrophysics Data System (ADS)
Aurell, Erik; Mejía-Monasterio, Carlos; Muratore-Ginanneschi, Paolo
2011-06-01
Thermodynamics of small systems has become an important field of statistical physics. Such systems are driven out of equilibrium by a control, and the question is naturally posed how such a control can be optimized. We show that optimization problems in small system thermodynamics are solved by (deterministic) optimal transport, for which very efficient numerical methods have been developed, and of which there are applications in cosmology, fluid mechanics, logistics, and many other fields. We show, in particular, that minimizing expected heat released or work done during a nonequilibrium transition in finite time is solved by the Burgers equation and mass transport by the Burgers velocity field. Our contribution hence considerably extends the range of solvable optimization problems in small system thermodynamics.
Sejnowski, Terrence J.; Poizner, Howard; Lynch, Gary; Gepshtein, Sergei; Greenspan, Ralph J.
2014-01-01
Human performance approaches that of an ideal observer and optimal actor in some perceptual and motor tasks. These optimal abilities depend on the capacity of the cerebral cortex to store an immense amount of information and to flexibly make rapid decisions. However, behavior only approaches these limits after a long period of learning while the cerebral cortex interacts with the basal ganglia, an ancient part of the vertebrate brain that is responsible for learning sequences of actions directed toward achieving goals. Progress has been made in understanding the algorithms used by the brain during reinforcement learning, which is an online approximation of dynamic programming. Humans also make plans that depend on past experience by simulating different scenarios, which is called prospective optimization. The same brain structures in the cortex and basal ganglia that are active online during optimal behavior are also active offline during prospective optimization. The emergence of general principles and algorithms for goal-directed behavior has consequences for the development of autonomous devices in engineering applications. PMID:25328167
Transiting Exoplanet Observations at Grinnell College
NASA Astrophysics Data System (ADS)
Sauerhaft, Julia; Slough, P.; Cale, B.; Kempton, E.
2014-01-01
Grinnell College, a small liberal arts college in Grinnell, Iowa with 1600 undergraduate students, is home to the Grant O. Gale Observatory. Over the past year, we have successfully detected extrasolar planets using the transit method with our 24-inch Cassegrain reflecting telescope equipped with a CCD camera. With little light pollution and an easily accessible observatory, Grinnell College is an optimal location for transiting exoplanet observations. With the current telescope set-up and CCD camera, we have taken time series data and created image calibration and post-processing programs that detect exoplanet transits at high photometric precision. In the future, we will continue to use these observation and data reduction procedures to conduct transiting exoplanet research. Goals for our research program include performing follow-up observations of transiting exoplanet candidates to confirm their planetary nature, searching for additional exoplanets in known planetary systems using the transit timing detection method, tracking long period transiting planets, and refining properties of exoplanets and their host stars. Ground-based transiting planet science is especially important in the post-Kepler era, and our dedicated mid-sized telescope with plenty of access to dark clear nights provides an ideal resource for a variety of follow up and exoplanet detection efforts.
Transition Handbook: Valley Transitional School Program.
ERIC Educational Resources Information Center
Virginia State Dept. of Rehabilitation Services, Richmond.
The handbook was developed by the 3-year Valley Transitional School Project, serving Augusta, Staunton, and Waynesboro schools, all located in Augusta County, Virginia. The purpose of the project was to develop and validate a model which would assist school youth with severe disabilities to make the transition from school to employment, in the…
Gas turbine combustor transition
Coslow, B.J.; Whidden, G.L.
1999-05-25
A method is described for converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit. 7 figs.
Gas turbine combustor transition
Coslow, Billy Joe; Whidden, Graydon Lane
1999-01-01
A method of converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit.
Lee, John R.
1975-01-01
Optimal fluoridation has been defined as that fluoride exposure which confers maximal cariostasis with minimal toxicity and its values have been previously determined to be 0.5 to 1 mg per day for infants and 1 to 1.5 mg per day for an average child. Total fluoride ingestion and urine excretion were studied in Marin County, California, children in 1973 before municipal water fluoridation. Results showed fluoride exposure to be higher than anticipated and fulfilled previously accepted criteria for optimal fluoridation. Present and future water fluoridation plans need to be reevaluated in light of total environmental fluoride exposure. PMID:1130041
Optimal back-to-front airplane boarding.
Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran
2013-06-01
The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective. PMID:23848727
Conceptualizing Transitions to Adulthood
ERIC Educational Resources Information Center
Wyn, Johanna
2014-01-01
This chapter provides an overview of theories of the transition to young adulthood. It sets out the argument for conceptual renewal and discusses some implications of new patterns of transition for adult education.
ERIC Educational Resources Information Center
Kneeland, Steven J.
1980-01-01
Having identified the problem of managerial transition in a previous article (CE 510 277), the author outlines a strategy for change which includes performance appraisal, definition of the management structure, and counselling for the individual in transition. (SK)
NASA Technical Reports Server (NTRS)
1985-01-01
The concept of a large disturbance bypass mechanism for the initiation of transition is reviewed and studied. This mechanism, or some manifestation thereof, is suspected to be at work in the boundary layers present in a turbine flow passage. Discussion is presented on four relevant subtopics: (1) the effect of upstream disturbances and wakes on transition; (2) transition prediction models, code development, and verification; (3) transition and turbulence measurement techniques; and (4) the hydrodynamic condition of low Reynolds number boundary layers.
Cosmological phase transitions
Kolb, E.W. |
1993-10-01
If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions.
Origins of evolutionary transitions.
Clarke, Ellen
2014-04-01
An 'evolutionary transition in individuality' or 'major transition' is a transformation in the hierarchical level at which natural selection operates on a population. In this article I give an abstract (i.e. level-neutral and substrate-neutral) articulation of the transition process in order to precisely understand how such processes can happen, especially how they can get started. PMID:24736161
ERIC Educational Resources Information Center
Regenwetter, Michel; Dana, Jason; Davis-Stober, Clintin P.
2011-01-01
Transitivity of preferences is a fundamental principle shared by most major contemporary rational, prescriptive, and descriptive models of decision making. To have transitive preferences, a person, group, or society that prefers choice option "x" to "y" and "y" to "z" must prefer "x" to "z". Any claim of empirical violations of transitivity by…
The Transition to Secondary Progressive Multiple Sclerosis
Wood, Fiona; Brain, Katherine E.; Edwards, Michelle; Jones, Rhiannon; Wallbank, Rachel; Robertson, Neil P.; Edwards, Adrian
2016-01-01
Background: Identifying the transition from relapsing-remitting to secondary progressive multiple sclerosis (SPMS) can be challenging for clinicians. Little previous research has explored how professionals experience working with patients during this specific stage of the disease. We explored the experiences of a group of multidisciplinary professionals who support patients in the transition to SPMS to describe this stage from a professional perspective. Methods: This qualitative semistructured interview study included 11 professionals (medical, nursing, and allied health professionals; specialists and generalists) working with patients with MS in South Wales, United Kingdom. Thematic analysis of the interview data was performed. Results: Two overarching themes were identified: the transition and providing support. The transition theme comprised issues related to recognizing and communicating about SPMS. Uncertainty influenced recognizing the transition and knowing how to discuss it with patients. The providing support theme included descriptions of challenging aspects of patient care, providing support for caregivers, using the multidisciplinary team, and working within service constraints. Providing adequate psychological support and engaging patients with self-management approaches were seen as particularly challenging. Conclusions: Caring for patients in the transition to SPMS generates specific challenges for professionals. Further research on health-care interactions and patients'/professionals' experiences regarding the transition phase may help identify strategies for professional development and learning and how to optimize the patient experience at this difficult stage of disease. PMID:27803641
Modeling the transition region
NASA Technical Reports Server (NTRS)
Singer, Bart A.
1993-01-01
The current status of transition-region models is reviewed in this report. To understand modeling problems, various flow features that influence the transition process are discussed first. Then an overview of the different approaches to transition-region modeling is given. This is followed by a detailed discussion of turbulence models and the specific modifications that are needed to predict flows undergoing laminar-turbulent transition. Methods for determining the usefulness of the models are presented, and an outlook for the future of transition-region modeling is suggested.
Gifts from Exoplanetary Transits
NASA Astrophysics Data System (ADS)
Narita, Norio
2009-08-01
The discovery of transiting extrasolar planets has enabled us to do a number of interesting studies. Transit photometry reveals the radius and the orbital inclination of transiting planets, which allows us to learn the true mass and density of the respective planets by the combined information from radial velocity (RV) measurements. In addition, follow-up observations of transiting planets, looking at such things as secondary eclipses, transit timing variations, transmission spectroscopy, and the Rossiter-McLaughlin effect, provide us information about their dayside temperatures, unseen bodies in systems, planetary atmospheres, and the obliquity of planetary orbits. Such observational information, which will provide us a greater understanding of extrasolar planets, is available only for transiting planets. Here, I briefly summarize what we can learn from transiting planets and introduce previous studies.
Assay optimization: a statistical design of experiments approach.
Altekar, Maneesha; Homon, Carol A; Kashem, Mohammed A; Mason, Steven W; Nelson, Richard M; Patnaude, Lori A; Yingling, Jeffrey; Taylor, Paul B
2007-03-01
With the transition from manual to robotic HTS in the last several years, assay optimization has become a significant bottleneck. Recent advances in robotic liquid handling have made it feasible to reduce assay optimization timelines with the application of statistically designed experiments. When implemented, they can efficiently optimize assays by rapidly identifying significant factors, complex interactions, and nonlinear responses. This article focuses on the use of statistically designed experiments in assay optimization.
Simulation of transition dynamics to high confinement in fusion plasmas
NASA Astrophysics Data System (ADS)
Nielsen, A. H.; Xu, G. S.; Madsen, J.; Naulin, V.; Juul Rasmussen, J.; Wan, B. N.
2015-12-01
The transition dynamics from the low (L) to the high (H) confinement mode in magnetically confined plasmas is investigated using a first-principles four-field fluid model. Numerical results are in agreement with measurements from the Experimental Advanced Superconducting Tokamak - EAST. Particularly, the slow transition with an intermediate dithering phase is well reproduced at proper parameters. The model recovers the power threshold for the L-H transition as well as the decrease in power threshold switching from single to double null configuration observed experimentally. The results are highly relevant for developing predictive models of the transition, essential for understanding and optimizing future fusion power reactors.
NASA Technical Reports Server (NTRS)
Patterson, Michael J.; Mohajeri, Kayhan
1991-01-01
The preliminary results of a test program to optimize a neutralizer design for 30 cm xenon ion thrusters are discussed. The impact of neutralizer geometry, neutralizer axial location, and local magnetic fields on neutralizer performance is discussed. The effect of neutralizer performance on overall thruster performance is quantified, for thruster operation in the 0.5-3.2 kW power range. Additionally, these data are compared to data published for other north-south stationkeeping (NSSK) and primary propulsion xenon ion thruster neutralizers.
The periodontal prosthesis mode of transition to an implant-supported dentition.
Hunt, Peter; Norkin, Frederic; Serrano, Julian
2006-01-01
In recent years, implant-supported reconstructions have become a welcome alternative to dentures for those who have lost their natural dentition. While the benefits of the final implant-supported reconstruction may be obvious, the planning and execution of therapy to achieve this result may be bewildering to many dentists. Four main modes of transfer have evolved: an uncontrolled or "haphazard" transition; the traditional "dentures first" mode, an immediate transition, and a staged transition. This article proposes an additional mode of transition called periodontal prosthesis, which has the potential to make the transition process smoother and more predictable while providing optimal retention of alveolar supporting structures and generating optimal esthetics.
Moons over Jupiter: transits and shadow transits
NASA Astrophysics Data System (ADS)
Rogers, J. H.; et al.
2003-06-01
There is no more beautiful illustration of orbital motions than the movements of Jupiter's satellites. Every six years, their movements are most strikingly displayed, when the jovian system is presented edge-on to Earth. This means that there is a higher frequency of multiple transits over the face of the planet, as all the moons transit across the equatorial zone, whereas in other years Ganymede and Callisto transit near the poles or not at all. Also, for a few months, the satellites pass in front of each other, displaying mutual eclipses and occultations. In 2002/2003 we have been able to observe a fine series of these multiple and mutual events. On the cover, and on these pages, are some of the highest-resolution images received.
Diffusion with optimal resetting
NASA Astrophysics Data System (ADS)
Evans, Martin R.; Majumdar, Satya N.
2011-10-01
We consider the mean time to absorption by an absorbing target of a diffusive particle with the addition of a process whereby the particle is reset to its initial position with rate r. We consider several generalizations of the model of Evans and Majumdar (2011 Phys. Rev. Lett.106 160601): (i) a space-dependent resetting rate r(x); (ii) resetting to a random position z drawn from a resetting distribution { P}(z); and (iii) a spatial distribution for the absorbing target PT(x). As an example of (i) we show that the introduction of a non-resetting window around the initial position can reduce the mean time to absorption provided that the initial position is sufficiently far from the target. We address the problem of optimal resetting, that is, minimizing the mean time to absorption for a given target distribution. For an exponentially decaying target distribution centred at the origin we show that a transition in the optimal resetting distribution occurs as the target distribution narrows.
Dynamical Transition in polypeptides
NASA Astrophysics Data System (ADS)
He, Yunfen; Markelz, Andrea
2008-03-01
Two of the possible causes for the so called dynamical transition (the rapid increase in flexibility for biomolecules at ˜ 200 K) are: thermally activated side chain diffusive motions with hydration dependent activation energies; or a glass transition in the biological water directly adjacent to the biomolecule. If the transition is strictly due to side chain activation, it should not depend on protein structure. Previously we demonstrated that the dynamical transition remains after tertiary structure was removed using THz time domain dielectric spectroscopy (0.2 -2.0 THz, 0.5-5ps). Here measurements on polyalanine as a function of chain length show that the dynamical transition does not occur for peptide length shorter than 5. However, the transition is observed for 5 mer and higher. Structural and simulation studies indicate that the 5 mer transiently occupies structured forms [1,2]. These results suggest that A) the dynamical transition is not due to thermally activated side chain motion and B) secondary structure is necessary for the dynamical transition. Secondary structure possibly induces sufficient ordering in the adjacent water to result in a fragile to strong glass transition resulting in increased protein flexibility [3]. [1] KAH Wildman et al. Solid State Nucl. Magn. Reson. 24 (2003) 94-109. [2] Yuguang Mu,et al. Proteins 58, (2005) 45-52. [3] S.H. Chen et al. PNAS (2006) 9012--9016.
Transitioning unmanned ground vehicle research technologies
NASA Astrophysics Data System (ADS)
Pacis, E. Biagtan; Everett, H. R.; Farrington, N.; Kogut, G.; Sights, B.; Kramer, T.; Thompson, M.; Bruemmer, D.; Few, D.
2005-05-01
The Technology Transfer project employs a spiral development process to enhance the functionality and autonomy of mobile systems in the Joint Robotics Program (JRP) Robotic Systems Pool (RSP). The approach is to harvest prior and on-going developments that address the technology needs identified by emergent in-theatre requirements and users of the RSP. The component technologies are evaluated on a transition platform to identify the best features of the different approaches, which are then integrated and optimized to work in harmony in a complete solution. The result is an enabling mechanism that continuously capitalizes on state-of-the-art results from the research environment to create a standardized solution that can be easily transitioned to ongoing development programs. This paper focuses on particular research areas, specifically collision avoidance, simultaneous localization and mapping (SLAM), and target-following, and describes the results of their combined integration and optimization over the past 12 months.
Communication: Optimal parameters for basin-hopping global optimization based on Tsallis statistics
NASA Astrophysics Data System (ADS)
Shang, C.; Wales, D. J.
2014-08-01
A fundamental problem associated with global optimization is the large free energy barrier for the corresponding solid-solid phase transitions for systems with multi-funnel energy landscapes. To address this issue we consider the Tsallis weight instead of the Boltzmann weight to define the acceptance ratio for basin-hopping global optimization. Benchmarks for atomic clusters show that using the optimal Tsallis weight can improve the efficiency by roughly a factor of two. We present a theory that connects the optimal parameters for the Tsallis weighting, and demonstrate that the predictions are verified for each of the test cases.
Communication: Optimal parameters for basin-hopping global optimization based on Tsallis statistics
Shang, C. Wales, D. J.
2014-08-21
A fundamental problem associated with global optimization is the large free energy barrier for the corresponding solid-solid phase transitions for systems with multi-funnel energy landscapes. To address this issue we consider the Tsallis weight instead of the Boltzmann weight to define the acceptance ratio for basin-hopping global optimization. Benchmarks for atomic clusters show that using the optimal Tsallis weight can improve the efficiency by roughly a factor of two. We present a theory that connects the optimal parameters for the Tsallis weighting, and demonstrate that the predictions are verified for each of the test cases.
Transition to Old Age (Transition to Retirement).
ERIC Educational Resources Information Center
Bergman, Simon
Several conceptualizations and definitions of retirement have been proposed. One of them--the three-stage transition process--can be illustrated from studies in Israel: (1) leaving the old role; (2) going through the act of formal separation; and (3) adjusting to the new situation and role. Today's higher rate of survival into later years means…
[SIAM conference on optimization
Not Available
1992-05-10
Abstracts are presented of 63 papers on the following topics: large-scale optimization, interior-point methods, algorithms for optimization, problems in control, network optimization methods, and parallel algorithms for optimization problems.
Transitioning between Clerkship Directors
ERIC Educational Resources Information Center
Soltys, Stephen M.; Pary, Robert J.; Robinson, Stephen W.; Markwell, Stephen J.
2011-01-01
Objective: The authors report on succession-planning for mid-level academic positions. Method: The authors describe the process of succession-planning between clerkship directors and the smooth transition resulting in one case. Results: Gradually transitioning allowed a new faculty person to assume the clerkship-director position with minimal…
Transitions in Spousal Caregiving.
ERIC Educational Resources Information Center
Burton, Lynda C.; Zdaniuk, Bozena; Schulz, Richard; Jackson, Sharon; Hirsch, Calvin
2003-01-01
Describes transitions over 5 years among community-dwelling elderly spouses into and within caregiving roles and associated health outcomes. The trajectory of health outcomes associated with caregiving was generally downward. Those who transitioned to heavy caregiving had more symptoms of depression, and poorer self-reported health and health…
ERIC Educational Resources Information Center
Test, David W.
2008-01-01
Postschool outcomes for students with disabilities have been dismal for quite some time now. Although recent data from the National Longitudinal Transition Study 2 indicate some improvement, students with severe intellectual disabilities continue to transition into segregated employment at unacceptable rates in spite of a multitude of studies,…
NASA Astrophysics Data System (ADS)
Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington
2016-04-01
We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU( N) require Weierstrass models that cannot be realized from the standard SU( N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.
Good Transitions = Great Starts!
ERIC Educational Resources Information Center
Our Children: The National PTA Magazine, 2012
2012-01-01
The smooth transition of outgoing and incoming board members and officers is of vital importance and can determine the PTA's success for years to come. The transition process is the responsibility of both incoming and outgoing officers and board members. It gives closure to those leaving their positions and allows those coming in to be properly…
Secondary Education Transition Model.
ERIC Educational Resources Information Center
Colorado State Univ., Ft. Collins.
The Secondary Education Transition Model project at Colorado State University-Fort Collins represents a local and state commitment to serve students with severe handicaps who are moving into community work and living roles. These comprehensive transition services begin at the secondary education level and extend into the adult service system. The…
ERIC Educational Resources Information Center
Ilfeld, Ellen M., Ed.; Hanssen, Elizabeth, Ed.
1997-01-01
If children are to benefit from a healthy, supportive early childhood experience, it is important to strengthen transitions between early childhood experiences in educational and care settings and the more formal educational system. This issue of Coordinator's Notebook focuses on strengthening linkages and transitions between home, preschool, and…
Nonlinear Transient Growth and Boundary Layer Transition
NASA Technical Reports Server (NTRS)
Paredes, Pedro; Choudhari, Meelan M.; Li, Fei
2016-01-01
Parabolized stability equations (PSE) are used in a variational approach to study the optimal, non-modal disturbance growth in a Mach 3 at plate boundary layer and a Mach 6 circular cone boundary layer. As noted in previous works, the optimal initial disturbances correspond to steady counter-rotating streamwise vortices, which subsequently lead to the formation of streamwise-elongated structures, i.e., streaks, via a lift-up effect. The nonlinear evolution of the linearly optimal stationary perturbations is computed using the nonlinear plane-marching PSE for stationary perturbations. A fully implicit marching technique is used to facilitate the computation of nonlinear streaks with large amplitudes. To assess the effect of the finite-amplitude streaks on transition, the linear form of plane- marching PSE is used to investigate the instability of the boundary layer flow modified by spanwise periodic streaks. The onset of bypass transition is estimated by using an N- factor criterion based on the amplification of the streak instabilities. Results show that, for both flow configurations of interest, streaks of sufficiently large amplitude can lead to significantly earlier onset of transition than that in an unperturbed boundary layer without any streaks.
Modeling and Fitting Exoplanet Transit Light Curves
NASA Astrophysics Data System (ADS)
Millholland, Sarah; Ruch, G. T.
2013-01-01
We present a numerical model along with an original fitting routine for the analysis of transiting extra-solar planet light curves. Our light curve model is unique in several ways from other available transit models, such as the analytic eclipse formulae of Mandel & Agol (2002) and Giménez (2006), the modified Eclipsing Binary Orbit Program (EBOP) model implemented in Southworth’s JKTEBOP code (Popper & Etzel 1981; Southworth et al. 2004), or the transit model developed as a part of the EXOFAST fitting suite (Eastman et al. in prep.). Our model employs Keplerian orbital dynamics about the system’s center of mass to properly account for stellar wobble and orbital eccentricity, uses a unique analytic solution derived from Kepler’s Second Law to calculate the projected distance between the centers of the star and planet, and calculates the effect of limb darkening using a simple technique that is different from the commonly used eclipse formulae. We have also devised a unique Monte Carlo style optimization routine for fitting the light curve model to observed transits. We demonstrate that, while the effect of stellar wobble on transit light curves is generally small, it becomes significant as the planet to stellar mass ratio increases and the semi-major axes of the orbits decrease. We also illustrate the appreciable effects of orbital ellipticity on the light curve and the necessity of accounting for its impacts for accurate modeling. We show that our simple limb darkening calculations are as accurate as the analytic equations of Mandel & Agol (2002). Although our Monte Carlo fitting algorithm is not as mathematically rigorous as the Markov Chain Monte Carlo based algorithms most often used to determine exoplanetary system parameters, we show that it is straightforward and returns reliable results. Finally, we show that analyses performed with our model and optimization routine compare favorably with exoplanet characterizations published by groups such as the
An optimal transition path for controlling greenhouse gases.
Nordhaus, W D
1992-11-20
Designing efficient policies to slow global warming requires an approach that combines economic tools with relations from the natural sciences. The dynamic integrated climate-economy (DICE) model presented here, an intertemporal general-equilibrium model of economic growth and climate change, can be used to investigate alternative approaches to slowing climate change. Evaluation of five policies suggests that a modest carbon tax would be an efficient approach to slow global warming, whereas rigid emissions- or climate-stabilization approaches would impose significant net economic costs. PMID:17778354
An optimal transition path for controlling greenhouse gases.
Nordhaus, W D
1992-11-20
Designing efficient policies to slow global warming requires an approach that combines economic tools with relations from the natural sciences. The dynamic integrated climate-economy (DICE) model presented here, an intertemporal general-equilibrium model of economic growth and climate change, can be used to investigate alternative approaches to slowing climate change. Evaluation of five policies suggests that a modest carbon tax would be an efficient approach to slow global warming, whereas rigid emissions- or climate-stabilization approaches would impose significant net economic costs.
NASA Astrophysics Data System (ADS)
Allahverdyan, Armen E.; Hovhannisyan, Karen; Mahler, Guenter
2010-05-01
We study a refrigerator model which consists of two n -level systems interacting via a pulsed external field. Each system couples to its own thermal bath at temperatures Th and Tc , respectively (θ≡Tc/Th<1) . The refrigerator functions in two steps: thermally isolated interaction between the systems driven by the external field and isothermal relaxation back to equilibrium. There is a complementarity between the power of heat transfer from the cold bath and the efficiency: the latter nullifies when the former is maximized and vice versa. A reasonable compromise is achieved by optimizing the product of the heat-power and efficiency over the Hamiltonian of the two systems. The efficiency is then found to be bounded from below by ζCA=(1)/(1-θ)-1 (an analog of the Curzon-Ahlborn efficiency), besides being bound from above by the Carnot efficiency ζC=(1)/(1-θ)-1 . The lower bound is reached in the equilibrium limit θ→1 . The Carnot bound is reached (for a finite power and a finite amount of heat transferred per cycle) for lnn≫1 . If the above maximization is constrained by assuming homogeneous energy spectra for both systems, the efficiency is bounded from above by ζCA and converges to it for n≫1 .
Predictability of critical transitions
NASA Astrophysics Data System (ADS)
Zhang, Xiaozhu; Kuehn, Christian; Hallerberg, Sarah
2015-11-01
Critical transitions in multistable systems have been discussed as models for a variety of phenomena ranging from the extinctions of species to socioeconomic changes and climate transitions between ice ages and warm ages. From bifurcation theory we can expect certain critical transitions to be preceded by a decreased recovery from external perturbations. The consequences of this critical slowing down have been observed as an increase in variance and autocorrelation prior to the transition. However, especially in the presence of noise, it is not clear whether these changes in observation variables are statistically relevant such that they could be used as indicators for critical transitions. In this contribution we investigate the predictability of critical transitions in conceptual models. We study the quadratic integrate-and-fire model and the van der Pol model under the influence of external noise. We focus especially on the statistical analysis of the success of predictions and the overall predictability of the system. The performance of different indicator variables turns out to be dependent on the specific model under study and the conditions of accessing it. Furthermore, we study the influence of the magnitude of transitions on the predictive performance.
Phase transitions in semidefinite relaxations
Javanmard, Adel; Montanari, Andrea; Ricci-Tersenghi, Federico
2016-01-01
Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large-scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful methods in this family and are surprisingly well suited for a broad range of problems where data take the form of matrices or graphs. It has been observed several times that when the statistical noise is small enough, SDP relaxations correctly detect the underlying combinatorial structures. In this paper we develop asymptotic predictions for several detection thresholds, as well as for the estimation error above these thresholds. We study some classical SDP relaxations for statistical problems motivated by graph synchronization and community detection in networks. We map these optimization problems to statistical mechanics models with vector spins and use nonrigorous techniques from statistical mechanics to characterize the corresponding phase transitions. Our results clarify the effectiveness of SDP relaxations in solving high-dimensional statistical problems. PMID:27001856
Phase transitions in semidefinite relaxations.
Javanmard, Adel; Montanari, Andrea; Ricci-Tersenghi, Federico
2016-04-19
Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large-scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful methods in this family and are surprisingly well suited for a broad range of problems where data take the form of matrices or graphs. It has been observed several times that when the statistical noise is small enough, SDP relaxations correctly detect the underlying combinatorial structures. In this paper we develop asymptotic predictions for several detection thresholds, as well as for the estimation error above these thresholds. We study some classical SDP relaxations for statistical problems motivated by graph synchronization and community detection in networks. We map these optimization problems to statistical mechanics models with vector spins and use nonrigorous techniques from statistical mechanics to characterize the corresponding phase transitions. Our results clarify the effectiveness of SDP relaxations in solving high-dimensional statistical problems. PMID:27001856
Transit management and replacement capital planning. Transportation research record
Not Available
1988-01-01
The 15 papers in this report deal with the following areas: planning priorities for replacement of transit assets; establishing a transit capital replacement account - the San Diego experience; use of life-cycle cost analysis in transit capital overhaul/replace decisions - an application to the PATH railcar fleet; methodology for projecting rail transit rehabilitation and replacement-capital financing needs; long-range transit fleet planning: defining and costing a replacement-only scenario for Seattle; strategic planning as a basis for capital-investment programming: case study of the regional transportation authority in Chicago; trolley bus and motor-coach operational cost comparisons utilizing section 15 data; strategic model for operator work-force planning in the transit industry; monitoring performance of new bus routes; optimization strategies for transit systems in urban corridors; data processing software for an automatic data-acquisition system in mass transit; determinants of superior performance in public transit: research opportunities using Section 15 data; life-cycle cost analysis of electronic registering fareboxes: a case study; cluster-sampling techniques for estimating transit patronage; recent changes in BART patronage: some findings on fare elasticities.
Momentum Injection in Tokamak Plasmas and Transitions to Reduced Transport
Parra, F. I.; Highcock, E. G.; Schekochihin, A. A.; Barnes, M.
2011-03-18
The effect of momentum injection on the temperature gradient in tokamak plasmas is studied. A plausible scenario for transitions to reduced transport regimes is proposed. The transition happens when there is sufficient momentum input so that the velocity shear can suppress or reduce the turbulence. However, it is possible to drive too much velocity shear and rekindle the turbulent transport. The optimal level of momentum injection is determined. The reduction in transport is maximized in the regions of low or zero magnetic shear.
Superconductivity in transition metals.
Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P
2015-03-13
A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified.
NASA Astrophysics Data System (ADS)
Kasper, Justin
2015-04-01
The heliosphere consists of the connective tissue of particles, fields and photons that mediate our interaction with the Sun and with interstellar space. Exploration of the heliosphere yields clues to the nature of environments we cannot reach ourselves, illuminating the composition of the solar interior, or the acceleration of cosmic rays in the galaxy. The heliosphere is also a laboratory for us to understand the fundamental physics of magnetized plasma, from heating and instabilities to coupling with neutral gas and dust. This talk will review some of the most exciting recent results in the heliosphere with a focus on transitions: what we can learn by exploring transitions within the heliosphere, how the heliosphere is responding to the long term transition in solar activity, and how our very view of the heliosphere is in transition with upcoming missions such as Solar Probe Plus, Solar Orbiter and IMAP.
Superconductivity in transition metals.
Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P
2015-03-13
A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. PMID:25666075
Alternative fuel transit buses
Motta, R.; Norton, P.; Kelly, K.
1996-10-01
The National Renewable Energy Laboratory (NREL) is a U.S. Department of Energy (DOE) national laboratory; this project was funded by DOE. One of NREL`s missions is to objectively evaluate the performance, emissions, and operating costs of alternative fuel vehicles so fleet managers can make informed decisions when purchasing them. Alternative fuels have made greater inroads into the transit bus market than into any other. Each year, the American Public Transit Association (APTA) surveys its members on their inventory and buying plans. The latest APTA data show that about 4% of the 50,000 transit buses in its survey run on an alternative fuel. Furthermore, 1 in 5 of the new transit buses that members have on order are alternative fuel buses. This program was designed to comprehensively and objectively evaluate the alternative fuels in use in the industry.
Transitions in biofilm formation
NASA Astrophysics Data System (ADS)
Gordon, Vernita; Thatcher, Travis; Cooley, Benjamin
2011-03-01
Biofilms are multicellular, dynamic communities formed by interacting unicellular organisms bound to a surface. Forming a biofilm is a developmental process, characterized by sequential changes in gene expression and behavior as bacteria and yeast progress from discrete, free-swimming cells though stages that arrive at a mature biofilm. We are developing automated metrics to identify key transitions in early biofilm formation as cells attach to a surface, populate that surface, and adhere to each other to form early microcolonies. Our metrics use high-throughput tracking and analysis of microscopy movies to localize these transitions in space and time. Each of these transitions is associated with a loss of entropy in the bacterial system and, therefore, with biological activity that drives this loss of entropy. Better understanding of these transitions will allow automated determination of the strength and turn-on of attractive cell-surface and cell-cell interactions as biofilm development progresses.
Ross, M; Japel, S; Boehler, R
2005-04-11
We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.
Palaeontology: turtles in transition.
Lee, Michael S Y
2013-06-17
One of the major remaining gaps in the vertebrate fossil record concerns the origin of turtles. The enigmatic little reptile Eunotosaurus could represent an important transitional form, as it has a rudimentary shell that resembles the turtle carapace.
The animation shows the difference between planet transit timing of single and multiple planet system. In tightly packed planetary systems, the gravitational pull of the planets among themselves ca...
Urban guideway transit workshop: Proceedings
Larsen, H. )
1992-03-01
On March 20--21, 1991, EPRI sponsored a workshop on urban guideway transit. The purpose of this workshop was to provide utility managers with increased knowledge about urban guideway transit options, public policy regarding transit, and the effect of transit options on utility operations. With this information utilities should be better prepared to make decisions about transit development in their service areas. The workshop also provided EPRI with ideas and information for developing an R D project plan for urban guideway transit.
Stability, transition and turbulence
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.
1987-01-01
A glimpse is provided of the research program in stability, transition, and turbulence based on numerical simulations. This program includes both the so-called abrupt and the restrained transition processes. Attention is confined to the prototype problems of channel flow and the parallel boundary layer in the former category and the Taylor-Couette flow in the latter category. It covers both incompressible flows and supersonic flows. Some representative results are presented.
Stability, transition and turbulence
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.
1987-01-01
A glimpse is provided of the research program in stability, transition and turbulence based on numerical simulations. This program includes both the so-called abrupt and the restrained transition processes. Attention is confined to the prototype problems of channel flow and the parallel boundary layer in the former category and the Taylor-Couette flow in the latter category. It covers both incompressible flows and supersonic flows. Some representative results are presented.
Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington
2016-04-13
In this study, we explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, wheremore » a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU(N) require Weierstrass models that cannot be realized from the standard SU(N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.« less
Effect of diamond trip geometries on boundary layer transition for hypersonic inlet
NASA Astrophysics Data System (ADS)
Zhao, H. Y.; Ni, H. L.; Zhang, Z. M.; Yi, M. R.
2016-10-01
In order to grasp the effect of diamond trip geometries on boundary layer transition of hypersonic inlet, an experiment at Mach number 6 in a hypersonic wind tunnel was performed for a hypersonic inlet. The heat transfers at the inlet wall were measured through the infrared thermography. The transition region was judged by the comparison of heat transfer between experiment and computation. Ten diamond forced transition trips were designed according to Modern Design of Experiments. The experimental results shown that the effect order of trip geometries on transition region were the trip height, distance between diamond elements and diagonal length of diamond element from the largest to the smallest. Transition region moved forward to the model tip with increasing trip height or trip length, or with decreasing distance between diamond elements, or with increasing diagonal length of element. The optimized configuration was obtained for diamond forced-transition trip when the optimization object was transition region.
NASA Astrophysics Data System (ADS)
Mayo, L. A.; Odenwald, S. F.
2002-09-01
December 6th, 1882 was the last transit of the planet Venus across the disk of the sun. It was heralded as an event of immense interest and importance to the astronomical community as well as the public at large. There have been only six such occurrences since Galileo first trained his telescope on the heavens in 1609 and on Venus in 1610 where he concluded that Venus had phases like the moon and appeared to get larger and smaller over time. Many historians consider this the final nail in the coffin of the Ptolemaic, Earth centered solar system. In addition, each transit has provided unique opportunities for discovery such as measurement and refinement of the astronomical unit, calculation of longitudes on the earth, and detection of Venus' atmosphere. The NASA Sun Earth Connection Education Forum in partnership with the Solar System Exploration Forum, DPS, and a number of NASA space missions is developing plans for an international education program centered around the June 8, 2004 Venus transit. The transit will be visible in its entirety from Europe and partially from the East Coast of the United States. We will use a series of robotic observatories including the Telescopes In Education network distributed in latitude to provide observations of the transit that will allow middle and high school students to calculate the A.U. through application of parallax. We will also use Venus transit as a probe of episodes in American history (e.g. 1769: revolutionary era, 1882: post civil war era, and 2004: modern era). Museums and planetariums in the US and Europe will offer real time viewing of the transit and conduct educational programs through professional development seminars, public lectures, and planetarium shows. We are interested in soliciting advice from the research community to coordinate professional research interests with this program.
Critical transition in the constrained traveling salesman problem
NASA Astrophysics Data System (ADS)
Andrecut, M.; Ali, M. K.
2001-04-01
We investigate the finite size scaling of the mean optimal tour length as a function of density of obstacles in a constrained variant of the traveling salesman problem (TSP). The computational experience pointed out a critical transition (at ρc~85%) in the dependence between the excess of the mean optimal tour length over the Held-Karp lower bound and the density of obstacles.
Sharp transitions in low-number quantum dots Bayesian magnetometry
NASA Astrophysics Data System (ADS)
Mazurek, Paweł; Horodecki, Michał; Czekaj, Łukasz; Horodecki, Paweł
2016-09-01
We consider Bayesian estimate of static magnetic field, characterized by a prior Gaussian probability distribution, in systems of a few electron quantum dot spins interacting with infinite temperature spin environment via hyperfine interaction. Sudden transitions among optimal states and measurements are observed. Usefulness of measuring occupation levels is shown for all times of the evolution, together with the role of entanglement in the optimal scenario. For low values of magnetic field, memory effects stemming from the interaction with environment provide limited metrological advantage.
A Flexible Transition State Searching Method for Atmospheric Reaction Systems
Lin, Xiao-Xiao; Liu, Yi-Rong; Huang, Teng; Chen, Jiao; Jiang, Shuai; Huang, Wei
2015-04-01
The precise and rapid exploration of transition states (TSs) is a major challenge when studying atmospheric reactions due to their complexity. In this work, a Monte Carlo Transition State Search Method (MCTSSM), which integrates Monte Carlo sampling technique with transition state optimization methods using an efficient computer script, has been developed for transition state searches. The efficiency and the potential application in atmospheric reactions of this method have been demonstrated by three types of test suits related to the reactions of atmospheric volatile organic compounds (VOCs): (1) OH addition, (2) OH hydrogen-abstraction, and (3) the other reactive group (e.g. Cl, O3, NO3), especially for the reaction of β-pinene-sCI (stabilized Criegee Intermediates) with water. It was shown that the application of this method with effective restricted parameters has greatly simplified the time-consuming and tedious manual search procedure for transition state (TS) of the bimolecular reaction systems.
A flexible transition state searching method for atmospheric reaction systems
NASA Astrophysics Data System (ADS)
Lin, Xiao-Xiao; Liu, Yi-Rong; Huang, Teng; Chen, Jiao; Jiang, Shuai; Huang, Wei
2015-04-01
The precise and rapid exploration of transition states (TSs) is a major challenge when studying atmospheric reactions due to their complexity. In this work, a Monte Carlo Transition State Search Method (MCTSSM), which integrates Monte Carlo sampling technique with transition state optimization methods using an efficient computer script, has been developed for transition state searches. The efficiency and the potential application in atmospheric reactions of this method have been demonstrated by three types of test suits related to the reactions of atmospheric volatile organic compounds (VOCs): (1) OH addition, (2) OH hydrogen-abstraction, and (3) the other reactive group (e.g. Cl, O3, NO3), especially for the reaction of β-pinene-sCI (stabilized Criegee Intermediates) with water. It was shown that the application of this method with effective restricted parameters has greatly simplified the time-consuming and tedious manual search procedure for transition state (TS) of the bimolecular reaction systems.
Improving Upon String Methods for Transition State Discovery.
Chaffey-Millar, Hugh; Nikodem, Astrid; Matveev, Alexei V; Krüger, Sven; Rösch, Notker
2012-02-14
Transition state discovery via application of string methods has been researched on two fronts. The first front involves development of a new string method, named the Searching String method, while the second one aims at estimating transition states from a discretized reaction path. The Searching String method has been benchmarked against a number of previously existing string methods and the Nudged Elastic Band method. The developed methods have led to a reduction in the number of gradient calls required to optimize a transition state, as compared to existing methods. The Searching String method reported here places new beads on a reaction pathway at the midpoint between existing beads, such that the resolution of the path discretization in the region containing the transition state grows exponentially with the number of beads. This approach leads to favorable convergence behavior and generates more accurate estimates of transition states from which convergence to the final transition states occurs more readily. Several techniques for generating improved estimates of transition states from a converged string or nudged elastic band have been developed and benchmarked on 13 chemical test cases. Optimization approaches for string methods, and pitfalls therein, are discussed.
Examining hydrogen transitions.
Plotkin, S. E.; Energy Systems
2007-03-01
This report describes the results of an effort to identify key analytic issues associated with modeling a transition to hydrogen as a fuel for light duty vehicles, and using insights gained from this effort to suggest ways to improve ongoing modeling efforts. The study reported on here examined multiple hydrogen scenarios reported in the literature, identified modeling issues associated with those scenario analyses, and examined three DOE-sponsored hydrogen transition models in the context of those modeling issues. The three hydrogen transition models are HyTrans (contractor: Oak Ridge National Laboratory), MARKAL/DOE* (Brookhaven National Laboratory), and NEMS-H2 (OnLocation, Inc). The goals of these models are (1) to help DOE improve its R&D effort by identifying key technology and other roadblocks to a transition and testing its technical program goals to determine whether they are likely to lead to the market success of hydrogen technologies, (2) to evaluate alternative policies to promote a transition, and (3) to estimate the costs and benefits of alternative pathways to hydrogen development.
Optimal disturbances in shearing and swirling flows
NASA Astrophysics Data System (ADS)
Daly, Conor
2011-11-01
Over the past twenty years transient energy density growth of linearly stable disturbances has shown to be the likely instigator for transition to turbulence in parallel shear flows. In this vein, optimal linear perturbations are calculated for two flows which have a mixture of forces acting on the fluid body. These are; rotating plane Couette flow (RPCF), which combines pressure-driven shear and swirl, and cylindrical Couette-Poiseuille flow (CCPF), which combines pressure-driven and Couette shear. Contours are presented of the maximum achievable linear transient growth, G, over the full range of wavenumbers within the linearly stable parameter regimes. Reference is made to experimental works on each flow and we examine the role that optimal disturbances have in the different transition phenomena that are observed. It is found that the contours of G fall qualitatively alongside the points of transition in the two flows, in support of the notion that large linear transient growth can act a precursor to transition. Despite the combination of effects acting on each fluid, transition in both flows falls in the range 102 < G <10 2 . 5 suggesting that in both flows the same mechanism may be at work. This work is funded by EPSRC.
Optimal foraging in semantic memory.
Hills, Thomas T; Jones, Michael N; Todd, Peter M
2012-04-01
Do humans search in memory using dynamic local-to-global search strategies similar to those that animals use to forage between patches in space? If so, do their dynamic memory search policies correspond to optimal foraging strategies seen for spatial foraging? Results from a number of fields suggest these possibilities, including the shared structure of the search problems-searching in patchy environments-and recent evidence supporting a domain-general cognitive search process. To investigate these questions directly, we asked participants to recover from memory as many animal names as they could in 3 min. Memory search was modeled over a representation of the semantic search space generated from the BEAGLE memory model of Jones and Mewhort (2007), via a search process similar to models of associative memory search (e.g., Raaijmakers & Shiffrin, 1981). We found evidence for local structure (i.e., patches) in memory search and patch depletion preceding dynamic local-to-global transitions between patches. Dynamic models also significantly outperformed nondynamic models. The timing of dynamic local-to-global transitions was consistent with optimal search policies in space, specifically the marginal value theorem (Charnov, 1976), and participants who were more consistent with this policy recalled more items.
Zhang, Xiao-Jie; Liu, Zhi-Pan
2015-10-13
To identify the low energy pathway for solid-to-solid phase transition has been a great challenge in physics and material science. This work develops a new theoretical method, namely, variable-cell double-ended surface walking (VC-DESW) to locate the transition state (TS) and deduce the pathway in solid phase transition. Inherited from the DESW method ( J. Chem. Theory Comput. 2013 , 9 , 5745 ) for molecular systems, the VC-DESW method implements an efficient mechanism to couple the lattice and atom degrees of freedom. The method features with fast pseudopathway building and accurate TS location for solid phase transition systems without requiring expensive Hessian computation and iterative pathway optimization. A generalized coordinate, consisting of the lattice vectors and the scaled atomic coordinates, is designed for describing the crystal potential energy surface (PES), which is able to capture the anisotropic behavior in phase transition. By comparing with the existing method for solid phase transition in different systems, we show that the VC-DESW method can be much more efficient for finding the TS in crystal phase transition. With the combination of the recently developed unbiased stochastic surface walking pathway sampling method, the VC-DESW is further utilized to resolve the lowest energy pathway of SiO2 α-quartz to quartz-II phase transition from many likely reaction pathways. These new methods provide a powerful platform for understanding and predicting the solid phase transition mechanism and kinetics.
Transition from School to Work.
ERIC Educational Resources Information Center
Milner, Eileen R.
1995-01-01
This brief informational flyer presents practical information on the transition from school to work for students who are deaf-blind or have other severe disabilities. After defining transition, the flyer offers guidelines on: the age at which transition services should be started, areas that should be considered in a coordinated transition plan,…
Navajo childbirth in transition.
Waxman, A G
1990-03-01
For the Navajo Indians, the transition from home-centered childbearing practices based on religious ritual to biomedically directed childbirth in hospitals was completed over a relatively short time in the middle decades of this century. For Anglo-American society, the acceptance of medically oriented childbirth occurred during an equally short period earlier in the century. The transition was driven for both by many common factors. For Navajo women it was additionally influenced by the social and economic changes that affected the Reservation following the beginning of the Second World War. This paper examines the changes in Navajo childbearing practices and, for comparison, those of the dominant American society. It reviews factors that permitted the acceptance of biomedical childbirth by Navajo women and explores the health implications of the transition. PMID:2233169
UTM: Universal Transit Modeller
NASA Astrophysics Data System (ADS)
Deeg, Hans J.
2014-12-01
The Universal Transit Modeller (UTM) is a light-curve simulator for all kinds of transiting or eclipsing configurations between arbitrary numbers of several types of objects, which may be stars, planets, planetary moons, and planetary rings. A separate fitting program, UFIT (Universal Fitter) is part of the UTM distribution and may be used to derive best fits to light-curves for any set of continuously variable parameters. UTM/UFIT is written in IDL code and its source is released in the public domain under the GNU General Public License.
Adaptation and optimization of biological transport networks.
Hu, Dan; Cai, David
2013-09-27
It has been hypothesized that topological structures of biological transport networks are consequences of energy optimization. Motivated by experimental observation, we propose that adaptation dynamics may underlie this optimization. In contrast to the global nature of optimization, our adaptation dynamics responds only to local information and can naturally incorporate fluctuations in flow distributions. The adaptation dynamics minimizes the global energy consumption to produce optimal networks, which may possess hierarchical loop structures in the presence of strong fluctuations in flow distribution. We further show that there may exist a new phase transition as there is a critical open probability of sinks, above which there are only trees for network structures whereas below which loops begin to emerge.
Stellar Variability Effects on Transit Spectroscopy
NASA Astrophysics Data System (ADS)
Zellem, Robert Thomas; Swain, Mark R.; Shkolnik, Evgenya; Line, Michael R.; Llama, Joe
2016-10-01
Stellar variability caused by surface magnetic activity poses a great challenge to accurately and precisely characterize the atmospheres of transiting exoplanets. We present a preliminary analysis of the effects of unocculted star spots at IR wavelengths on planetary transmission and emission spectra. We will explore how stellar variability changes the derived exoplanet atmospheric parameters inferred through retrievals for a group of exoplanetary hosts stars. Our study includes stars ranging in activity levels from an inactive sun to a very active late-type star, and a range of planetary masses from super-Earths to Jupiters. These effects will be especially important for the high precision measurements (<100 ppm) needed to characterize the atmospheric composition of smaller planets. This work is critical for optimizing the exoplanet observing program of JWST, which will study known habitable zone transiting planets as well as new ones found by TESS orbiting nearby M dwarfs, which are more active than solar-type stars.
NASA Astrophysics Data System (ADS)
Marec, J. P.
The optimization of rendezvous and transfer orbits is introduced. Optimal transfer is defined and propulsion system modeling is outlined. Parameter optimization, including the Hohmann transfer, is discussed. Optimal transfer in general, uniform, and central gravitational fields is covered. Interplanetary rendezvous is treated.
Nursing Role Transition Preceptorship
ERIC Educational Resources Information Center
Batory, Susan M.
2014-01-01
The preceptorship clinical experience in a practical nursing (PN) program at a Midwestern community college is considered crucial to the PN students' transition from novice nurse to professional nurse. However, no research has been available to determine whether the preceptorship clinical accomplishes its purpose. A case study was conducted to…
Singh, Seema
2006-10-01
India is a country in transition, and so is its science. Scientific institutions, researchers, regulatory agencies, and government policies are in a state of flux as changes are instigated to overcome the bureaucracy and inertia that are characteristic of a populous developing nation.
Variational transition state theory
Truhlar, D.G.
1993-12-01
This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.
ERIC Educational Resources Information Center
Varmecky, Jane Hyde
2012-01-01
Many adults return to formal learning situations to pursue lifelong learning goals because their lives are in transition from dealing with real-life problems such as divorce and re-marriage. The purpose of this study was to describe what couples learned that contributed to the success of their subsequent marriages and how they learned it. The…
ERIC Educational Resources Information Center
Bundy, Michael L., Ed.; Gumaer, James, Ed.
1984-01-01
Focuses on disrupted families and the role of the school counselor in helping children adjust. Describes characteristics of healthy families, and discusses the transition to the blended family, effects of divorce groups on children's classroom behavior, counseling children in stepfamilies, single-parent families, and parenting strengths of single…
ERIC Educational Resources Information Center
Molina, Carla A.
1995-01-01
Discusses transitional situations of concurrent computer-based training (CBT) that occur in organizations, and provides instructional designers with adaptable checklists to use when communicating with managers and programmers about the tasks performed and the tools needed in designing and developing CBT. Tables present steps, applications,…
ERIC Educational Resources Information Center
Castles, Stephen; And Others
1982-01-01
The Foundation for Education with Production was organized to help African countries make the transition from colonial economies to socialism by providing an international network of resources to support educational innovations linking education with production. The theoretical basis for the foundation's work and its current activities are…
ERIC Educational Resources Information Center
Johnston, William; McAllister, Alex M.
2012-01-01
Successful outcomes for a "Transition Course in Mathematics" have resulted from two unique design features. The first is to run the course as a "survey course" in mathematics, introducing sophomore-level students to a broad set of mathematical fields. In this single mathematics course, undergraduates benefit from an introduction of proof…
Transition at hypersonic speeds
NASA Technical Reports Server (NTRS)
Morkovin, Mark V.
1987-01-01
Certain conjectures on the physics of instabilities in high-speed flows are discussed and the state of knowledge of hypersonic transition summarized. The case is made for an unpressured systematic research program in this area consisting of controlled microscopic experiments, theory, and numerical simulations.
ERIC Educational Resources Information Center
Sherman, Jill Z.; Osborn, Sandra R.
Vocationally at-risk students have one or a combination of handicaps affecting mobility, coordination, communication, self-care and/or cognition which may significantly interfere with the goals of successful student-to-adult transition, namely employment, productive work, and independent community living. A program for students with physical…
String mediated phase transitions
NASA Technical Reports Server (NTRS)
Copeland, ED; Haws, D.; Rivers, R.; Holbraad, S.
1988-01-01
It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed.
Singing Smoothes Classroom Transitions
ERIC Educational Resources Information Center
Mathews, Sarah E.
2012-01-01
Just as humming a merry tune helped Snow White and her furry animal friends to quickly clean a filthy cottage in the movie "Snow White and the Seven Dwarfs" (Disney & Cottrell, 1937), singing can be an effective way to help keep young children fully engaged during classroom transitions. The purposes of this article are to: (1) consider why…
ERIC Educational Resources Information Center
Britton, Patti O., Ed.; McGee, Michael, Ed.
1987-01-01
This issue of "Emphasis" deals with families in transition, providing some model programs for the new family and some historical perspectives on how families have developed over time. Articles include: (1) "Nostalgia on the Right" (Nancy Theriot); (2) "Heart to Heart" (Nancy Harrington-MacLennan); (3) "The Media Get the Message" (Janet Alyn); (4)…
Transition and the Education of the New South African Citizen
ERIC Educational Resources Information Center
Hammett, Daniel; Staeheli, Lynn
2013-01-01
South Africa's democratic transition was a time of optimism, with immense hopes pinned on the youth who would be educated to see themselves as equal citizens. It was also a time of pragmatic decision making, not least in the education sector, which would shape the future of the country. Negotiating the imperatives of redress, development, and…
Topic Transition in Educational Videos Using Visually Salient Words
ERIC Educational Resources Information Center
Gandhi, Ankit; Biswas, Arijit; Deshmukh, Om
2015-01-01
In this paper, we propose a visual saliency algorithm for automatically finding the topic transition points in an educational video. First, we propose a method for assigning a saliency score to each word extracted from an educational video. We design several mid-level features that are indicative of visual saliency. The optimal feature combination…
Water's second glass transition.
Amann-Winkel, Katrin; Gainaru, Catalin; Handle, Philip H; Seidl, Markus; Nelson, Helge; Böhmer, Roland; Loerting, Thomas
2013-10-29
The glassy states of water are of common interest as the majority of H2O in space is in the glassy state and especially because a proper description of this phenomenon is considered to be the key to our understanding why liquid water shows exceptional properties, different from all other liquids. The occurrence of water's calorimetric glass transition of low-density amorphous ice at 136 K has been discussed controversially for many years because its calorimetric signature is very feeble. Here, we report that high-density amorphous ice at ambient pressure shows a distinct calorimetric glass transitions at 116 K and present evidence that this second glass transition involves liquid-like translational mobility of water molecules. This "double Tg scenario" is related to the coexistence of two liquid phases. The calorimetric signature of the second glass transition is much less feeble, with a heat capacity increase at Tg,2 about five times as large as at Tg,1. By using broadband-dielectric spectroscopy we resolve loss peaks yielding relaxation times near 100 s at 126 K for low-density amorphous ice and at 110 K for high-density amorphous ice as signatures of these two distinct glass transitions. Temperature-dependent dielectric data and heating-rate-dependent calorimetric data allow us to construct the relaxation map for the two distinct phases of water and to extract fragility indices m = 14 for the low-density and m = 20-25 for the high-density liquid. Thus, low-density liquid is classified as the strongest of all liquids known ("superstrong"), and also high-density liquid is classified as a strong liquid. PMID:24101518
NASA Technical Reports Server (NTRS)
Doyle, Laurance R.
1998-01-01
During the past five years we have pursued the detection of extrasolar planets by the photometric transit method, i.e. the detection of a planet by watching for a drop in the brightness of the light as it crosses in front of a star. The planetary orbit must cross the line-of-sight and so most systems will not be lined up for such a transit to ever occur. However, we have looked at eclipsing binary systems which are already edge-on. Such systems must be very small in size as this makes the differential light change due to a transit much greater for a given planet size (the brightness difference will be proportional to the area of the transiting planet to the disc area of the star). Also, the planet forming region should be closer to the star as small stars are generally less luminous (that is, if the same thermal regime for planet formation applies as in the solar system). This led to studies of the habitable zone around other stars, as well. Finally, we discovered that our data could be used to detect giant planets without transits as we had been carefully timing the eclipses of the stars (using a GPS antenna for time) and this will drift by being offset by any giant planets orbiting around the system, as well. The best summary of our work may be to just summarize the 21 refereed papers produced during the time of this grant. This will be done is chronological order and in each section separately.
Electrothermal design aspects of transitioning solid armatures
NASA Astrophysics Data System (ADS)
Schoolderman, A. J.; de Zeeuw, W. A.; Koops, M.
1993-01-01
To optimize erosion-free rail accelerator launch of solid brush armatures, a 2D model and an analytical model are used to study the temperature distribution, the coefficient of friction and the transitioning behavior of U-shaped solid armatures made of Cu, Al, Mo, and Ti during electromagnetic launch. In order to experimentally verify the insights gained from these theoretical studies, recently developed diagnostics are applied. The growth potential of solid armatures for weapons applications is highlighted by considering such materials as Ti and Mo.
Optimization of composite structures
NASA Technical Reports Server (NTRS)
Stroud, W. J.
1982-01-01
Structural optimization is introduced and examples which illustrate potential problems associated with optimized structures are presented. Optimized structures may have very low load carrying ability for an off design condition. They tend to have multiple modes of failure occurring simultaneously and can, therefore, be sensitive to imperfections. Because composite materials provide more design variables than do metals, they allow for more refined tailoring and more extensive optimization. As a result, optimized composite structures can be especially susceptible to these problems.
Multiscale optimization in neural nets.
Mjolsness, E; Garrett, C D; Miranker, W L
1991-01-01
One way to speed up convergence in a large optimization problem is to introduce a smaller, approximate version of the problem at a coarser scale and to alternate between relaxation steps for the fine-scale and coarse-scale problems. Such an optimization method for neural networks governed by quite general objective functions is presented. At the coarse scale, there is a smaller approximating neural net which, like the original net, is nonlinear and has a nonquadratic objective function. The transitions and information flow from fine to coarse scale and back do not disrupt the optimization, and the user need only specify a partition of the original fine-scale variables. Thus, the method can be applied easily to many problems and networks. There is generally about a fivefold improvement in estimated cost under the multiscale method. In the networks to which it was applied, a nontrivial speedup by a constant factor of between two and five was observed, independent of problem size. Further improvements in computational cost are very likely to be available, especially for problem-specific multiscale neural net methods.
Radiation Shielding Optimization on Mars
NASA Technical Reports Server (NTRS)
Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.
2013-01-01
Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.
Klammer, Martin; Dybowski, J Nikolaj; Hoffmann, Daniel; Schaab, Christoph
2015-01-01
Multivariate biomarkers that can predict the effectiveness of targeted therapy in individual patients are highly desired. Previous biomarker discovery studies have largely focused on the identification of single biomarker signatures, aimed at maximizing prediction accuracy. Here, we present a different approach that identifies multiple biomarkers by simultaneously optimizing their predictive power, number of features, and proximity to the drug target in a protein-protein interaction network. To this end, we incorporated NSGA-II, a fast and elitist multi-objective optimization algorithm that is based on the principle of Pareto optimality, into the biomarker discovery workflow. The method was applied to quantitative phosphoproteome data of 19 non-small cell lung cancer (NSCLC) cell lines from a previous biomarker study. The algorithm successfully identified a total of 77 candidate biomarker signatures predicting response to treatment with dasatinib. Through filtering and similarity clustering, this set was trimmed to four final biomarker signatures, which then were validated on an independent set of breast cancer cell lines. All four candidates reached the same good prediction accuracy (83%) as the originally published biomarker. Although the newly discovered signatures were diverse in their composition and in their size, the central protein of the originally published signature - integrin β4 (ITGB4) - was also present in all four Pareto signatures, confirming its pivotal role in predicting dasatinib response in NSCLC cell lines. In summary, the method presented here allows for a robust and simultaneous identification of multiple multivariate biomarkers that are optimized for prediction performance, size, and relevance.
Alternative fuel transit buses: The Pierce Transit Success Story
1996-10-01
The Pierce transit program for operating mass transit buses on compressed natural gas (CNG) is described. Cost, reliability, fuel efficiency, emission of combustion products, and future trends are discussed.
ERIC Educational Resources Information Center
Kaehne, Axel; Beyer, Stephen
2009-01-01
The paper reports the findings of a study of professionals in strategic and operational positions who were involved in transition planning for young people with learning disabilities. Respondents were asked to comment on what they regarded as the optimal aim and outcome of transition from school to post-school placements. The results illustrate…
A Qualitative Analysis of an Advanced Practice Nurse-Directed Transitional Care Model Intervention
ERIC Educational Resources Information Center
Bradway, Christine; Trotta, Rebecca; Bixby, M. Brian; McPartland, Ellen; Wollman, M. Catherine; Kapustka, Heidi; McCauley, Kathleen; Naylor, Mary D.
2012-01-01
Purpose: The purpose of this study was to describe barriers and facilitators to implementing a transitional care intervention for cognitively impaired older adults and their caregivers lead by advanced practice nurses (APNs). Design and Methods: APNs implemented an evidence-based protocol to optimize transitions from hospital to home. An…
75 FR 76921 - Tobacco Transition Payment Program; Tobacco Transition Assessments
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-10
... Corporation 7 CFR Part 1463 RIN 0560-AH30 Tobacco Transition Payment Program; Tobacco Transition Assessments... Commodity Credit Corporation (CCC) is modifying the regulations for the Tobacco Transition Payment Program (TTPP) to clarify, consistent with current practice and as required by the Fair and Equitable...
Transition Planning: A Team Effort. NICHCY Transition Summary, TS10.
ERIC Educational Resources Information Center
Gutierrez, Mary Kate
This summary on transition planning provides ideas and information on how students, families, school personnel, service providers, and others can work together to help students with a disability make a smooth transition after leaving high school. It focuses on creative transition planning and services that use all the resources that exist in…
Particle Swarm Optimization Toolbox
NASA Technical Reports Server (NTRS)
Grant, Michael J.
2010-01-01
The Particle Swarm Optimization Toolbox is a library of evolutionary optimization tools developed in the MATLAB environment. The algorithms contained in the library include a genetic algorithm (GA), a single-objective particle swarm optimizer (SOPSO), and a multi-objective particle swarm optimizer (MOPSO). Development focused on both the SOPSO and MOPSO. A GA was included mainly for comparison purposes, and the particle swarm optimizers appeared to perform better for a wide variety of optimization problems. All algorithms are capable of performing unconstrained and constrained optimization. The particle swarm optimizers are capable of performing single and multi-objective optimization. The SOPSO and MOPSO algorithms are based on swarming theory and bird-flocking patterns to search the trade space for the optimal solution or optimal trade in competing objectives. The MOPSO generates Pareto fronts for objectives that are in competition. A GA, based on Darwin evolutionary theory, is also included in the library. The GA consists of individuals that form a population in the design space. The population mates to form offspring at new locations in the design space. These offspring contain traits from both of the parents. The algorithm is based on this combination of traits from parents to hopefully provide an improved solution than either of the original parents. As the algorithm progresses, individuals that hold these optimal traits will emerge as the optimal solutions. Due to the generic design of all optimization algorithms, each algorithm interfaces with a user-supplied objective function. This function serves as a "black-box" to the optimizers in which the only purpose of this function is to evaluate solutions provided by the optimizers. Hence, the user-supplied function can be numerical simulations, analytical functions, etc., since the specific detail of this function is of no concern to the optimizer. These algorithms were originally developed to support entry
Sander, O.R.
1982-06-01
After describing the transition region between the LAMPF drift-tube linac and side-coupled linac, we discuss the function of the region, its present shortcomings, and the need for a redesign. Then we present the new design, its advantages, and its expected performance. Included are detailed results of beam-dynamics studies giving the ranges of input- and output-beam shapes that can be successfully matched in the new transition region. To improve the present operation of the two linacs, we suggest small changes that will allow us to easily match the beam between the two linacs. Finally we describe the methods used in our beam-dynamic studies so that effects of future improvements to the new design can be examined.
Radiative Transitions in Charmonium
Jozef Dudek; Robert Edwards; David Richards
2005-10-01
The form factors for the radiative transitions between charmonium mesons are investigated. We employ an anisotropic lattice using a Wilson gauge action, and domain-wall fermion action. We extrapolate the form factors to Q{sup 2} = 0, corresponding to a real photon, using quark-model-inspired functions. Finally, comparison is made with photocouplings extracted from the measured radiative widths, where known. Our preliminary results find photocouplings commensurate with these experimentally extracted values.
The major evolutionary transitions.
Szathmáry, E; Smith, J M
1995-03-16
There is no theoretical reason to expect evolutionary lineages to increase in complexity with time, and no empirical evidence that they do so. Nevertheless, eukaryotic cells are more complex than prokaryotic ones, animals and plants are more complex than protists, and so on. This increase in complexity may have been achieved as a result of a series of major evolutionary transitions. These involved changes in the way information is stored and transmitted.
High speed transition prediction
NASA Technical Reports Server (NTRS)
Gasperas, Gediminis
1992-01-01
The main objective of this work period was to develop, acquire and apply state-of-the-art tools for the prediction of transition at high speeds at NASA Ames. Although various stability codes as well as basic state codes were acquired, the development of a new Parabolized Stability Equation (PSE) code was minimal. The time that was initially allocated for development was used on other tasks, in particular for the Leading Edge Suction problem, in acquiring proficiency in various graphics tools, and in applying these tools to evaluate various Navier-Stokes and Euler solutions. The second objective of this work period was to attend the Transition and Turbulence Workshop at NASA Langley in July and August, 1991. A report on the Workshop follows. From July 8, 1991 to August 2, 1991, the author participated in the Transition and Turbulence Workshop at NASA Langley. For purposes of interest here, analysis can be said to consist of solving simplified governing equations by various analytical methods, such as asymptotic methods, or by use of very meager computer resources. From the composition of the various groups at the Workshop, it can be seen that analytical methods are generally more popular in Great Britain than they are in the U.S., possibly due to historical factors and the lack of computer resources. Experimenters at the Workshop were mostly concerned with subsonic flows, and a number of demonstrations were provided, among which were a hot-wire experiment to probe the boundary layer on a rotating disc, a hot-wire rake to map a free shear layer behind a cylinder, and the use of heating strips on a flat plate to control instability waves and consequent transition. A highpoint of the demonstrations was the opportunity to observe the rather noisy 'quiet' supersonic pilot tunnel in operation.
Ridzal, Danis
2007-03-01
Aristos is a Trilinos package for nonlinear continuous optimization, based on full-space sequential quadratic programming (SQP) methods. Aristos is specifically designed for the solution of large-scale constrained optimization problems in which the linearized constraint equations require iterative (i.e. inexact) linear solver techniques. Aristos' unique feature is an efficient handling of inexactness in linear system solves. Aristos currently supports the solution of equality-constrained convex and nonconvex optimization problems. It has been used successfully in the area of PDE-constrained optimization, for the solution of nonlinear optimal control, optimal design, and inverse problems.
2007-03-01
Aristos is a Trilinos package for nonlinear continuous optimization, based on full-space sequential quadratic programming (SQP) methods. Aristos is specifically designed for the solution of large-scale constrained optimization problems in which the linearized constraint equations require iterative (i.e. inexact) linear solver techniques. Aristos' unique feature is an efficient handling of inexactness in linear system solves. Aristos currently supports the solution of equality-constrained convex and nonconvex optimization problems. It has been used successfully in the areamore » of PDE-constrained optimization, for the solution of nonlinear optimal control, optimal design, and inverse problems.« less
NASA Technical Reports Server (NTRS)
1992-01-01
NASA science publications have used the metric system of measurement since 1970. Although NASA has maintained a metric use policy since 1979, practical constraints have restricted actual use of metric units. In 1988, an amendment to the Metric Conversion Act of 1975 required the Federal Government to adopt the metric system except where impractical. In response to Public Law 100-418 and Executive Order 12770, NASA revised its metric use policy and developed this Metric Transition Plan. NASA's goal is to use the metric system for program development and functional support activities to the greatest practical extent by the end of 1995. The introduction of the metric system into new flight programs will determine the pace of the metric transition. Transition of institutional capabilities and support functions will be phased to enable use of the metric system in flight program development and operations. Externally oriented elements of this plan will introduce and actively support use of the metric system in education, public information, and small business programs. The plan also establishes a procedure for evaluating and approving waivers and exceptions to the required use of the metric system for new programs. Coordination with other Federal agencies and departments (through the Interagency Council on Metric Policy) and industry (directly and through professional societies and interest groups) will identify sources of external support and minimize duplication of effort.
Youths Transitioning as Adult Learners
ERIC Educational Resources Information Center
Davis, C. Amelia
2014-01-01
This chapter considers how transitions to adulthood have been historically represented and presents alternative ways of thinking about transitions to adulthood through the context of adult basic education programs.
ERIC Educational Resources Information Center
Burke, Catherine G.
1982-01-01
Criticizes eight commonly held notions about the value of mass transit systems in public transportation programs. Alternative approaches for improving the quality and quantity of urban transit systems are discussed. (AM)
Buckley Prize Talk: The Suprerconductor-(Metal)-Insulator Transition
NASA Astrophysics Data System (ADS)
Kapitulnik, Aharon
2015-03-01
While the classical theory of phase transitions has been extraordinarily successful, there are several reasons to exercise caution when applying this approach to the zero temperature superconducting transition. First, experimental identification of the relevant phases requires extrapolation to zero temperature, which becomes complicated, especially when one needs to identify sources of dissipation. In addition, since superconductivity may be highly inhomogeneous as appreciable superconducting order parameter may be concentrated in ``superconducting puddles'' due to disorder and/or spontaneous phase separation, the nature of the quantum phase transition to a superconducting state may be highly anomalous, where the system attempts to optimizes the formation of puddles with the Josephson coupling among them to obtain global superconductivity. In this talk we will review some of the consequences of these considerations, emphasizing the possible emergence of anomalous metallic phases close to the superconductor-insulator transition.
PYTRANSIT: fast and easy exoplanet transit modelling in PYTHON
NASA Astrophysics Data System (ADS)
Parviainen, Hannu
2015-07-01
We present a fast and user friendly exoplanet transit light-curve modelling package PYTRANSIT, implementing optimized versions of the Giménez and Mandel & Agol transit models. The package offers an object-oriented PYTHON interface to access the two models implemented natively in FORTRAN with OpenMP parallelization. A partial OpenCL version of the quadratic Mandel-Agol model is also included for GPU-accelerated computations. The aim of PYTRANSIT is to facilitate the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations, as a part of a researcher's programming toolkit for building complex, problem-specific analyses.
The transition to agricultural sustainability
Ruttan, Vernon W.
1999-01-01
The transition to sustainable growth in agricultural production during the 21st century will take place within the context of a transition to a stable population and a possible transition to a stable level of material consumption. If the world fails to successfully navigate a transition to sustainable growth in agricultural production, the failure will be due more to a failure in the area of institutional innovation than to resource and environmental constraints. PMID:10339524
Visual Analytics Technology Transition Progress
Scholtz, Jean; Cook, Kristin A.; Whiting, Mark A.; Lemon, Douglas K.; Greenblatt, Howard
2009-09-23
The authors provide a description of the transition process for visual analytic tools and contrast this with the transition process for more traditional software tools. This paper takes this into account and describes a user-oriented approach to technology transition including a discussion of key factors that should be considered and adapted to each situation. The progress made in transitioning visual analytic tools in the past five years is described and the challenges that remain are enumerated.
Reconstructing Transition Knowledge in Taiwan
ERIC Educational Resources Information Center
Cheng, Chen-chen
2012-01-01
Taking a post-colonial stand and using school to work transition as an example, the author re-examines the special education discourses in Taiwan and attempts to construct alternate understandings of transition from sociological and cultural perspectives. A review of past transition literature and a survey of the educational background of the…
Wald, Arnold
2002-08-01
The diagnosis of slow transit functional constipation is based upon diagnostic testing of patients with idiopathic constipation who responded poorly to conservative measures such as fiber supplements, fluids, and stimulant laxatives. These tests include barium enema or colonoscopy, colonic transit of radio-opaque markers, anorectal manometry, and expulsion of a water-filled balloon. Plain abdominal films can identify megacolon, which can be further characterized by barium or gastrografin studies. Colonic transit of radio-opaque markers identifies patients with slow transit with stasis of markers in the proximal colon. However, anorectal function should be characterized to exclude outlet dysfunction, which may coexist with colonic inertia. Because slow colonic transit is defined by studies during which patients consume a high-fiber diet, fiber supplements are generally not effective, nor are osmotic laxatives that consist of unabsorbed sugars. Stimulant laxatives are considered first-line therapy, although studies often show a diminished colonic motor response to such agents. There is no evidence to suggest that chronic use of such laxatives is harmful if they are used two to three times per week. Polyethylene glycol with or without electrolytes may be useful in a minority of patients, often combined with misoprostol. I prefer to start with misoprostol 200 mg every other morning and increase to tolerance or efficacy. I see no advantage in prescribing misoprostol on a TID or QID basis or even daily because it increases cramping unnecessarily. This drug is not acceptable in young women who wish to become pregnant. An alternative may be colchicine, which is reported to be effective when given as 0.6 mg TID. Long-term efficacy has not been studied. Finally, biofeedback is a risk-free approach that has been reported as effective in approximately 60% of patients with slow transit constipation in the absence of outlet dysfunction. Although difficult to understand
Multidisciplinary Optimization for Aerospace Using Genetic Optimization
NASA Technical Reports Server (NTRS)
Pak, Chan-gi; Hahn, Edward E.; Herrera, Claudia Y.
2007-01-01
In support of the ARMD guidelines NASA's Dryden Flight Research Center is developing a multidisciplinary design and optimization tool This tool will leverage existing tools and practices, and allow the easy integration and adoption of new state-of-the-art software. Optimization has made its way into many mainstream applications. For example NASTRAN(TradeMark) has its solution sequence 200 for Design Optimization, and MATLAB(TradeMark) has an Optimization Tool box. Other packages, such as ZAERO(TradeMark) aeroelastic panel code and the CFL3D(TradeMark) Navier-Stokes solver have no built in optimizer. The goal of the tool development is to generate a central executive capable of using disparate software packages ina cross platform network environment so as to quickly perform optimization and design tasks in a cohesive streamlined manner. A provided figure (Figure 1) shows a typical set of tools and their relation to the central executive. Optimization can take place within each individual too, or in a loop between the executive and the tool, or both.
Structural transitions in nanoscale systems
NASA Astrophysics Data System (ADS)
Yoon, Mina
In this work I investigate three different materials: nanoscale carbon systems, ferrofluid systems, and molecular-electronic devices. In particular, my study is focused on the theoretical understanding of structural changes and the associated electronic, mechanical, and magnetic properties of these materials. To study the equilibrium packing of fullerenes in carbon nanotube peapods optimization techniques were applied. In agreement with experimental measurements, my results for nanotubes containing fullerenes with 60--84 atoms indicate that the axial separation between the fullerenes is smaller than in the bulk crystal. The reduction of the inter-fullerene distance and also the structural relaxation of fullerenes result from a large internal pressure within the peapods. This naturally induced "static" pressure may qualify nanotubes as nanoscale autoclaves for chemical reactions. Combining total energy calculations with a search of phase space, I investigated the microscopic fusion mechanism of C60 fullerenes. I show that the (2+2) cycloaddition reaction, a necessary precursor for fullerene fusion, can be accelerated inside a nanotube. Fusion occurs along the minimum energy path as a finite sequence of Stone-Wales (SW) transformations. A detailed analysis of the transition states shows that Stone-Wales transformations are multi-step processes. I propose a new microscopic mechanism to explain the unusually fast fusion process of carbon nanotubes. The detailed pathway for two adjacent (5, 5) nanotubes to gradually merge into a (10, 10) tube, and the transition states have been identified. The propagation of the fused region is energetically favorable and proceeds in a morphology reminiscent of a Y-junction via a so called zipper mechanism, involving only SW bond rearrangements with low activation barriers. Using density functional theory, the equilibrium structure, stability, and electronic properties of nanostructured, hydrogen terminated diamond fragments have been
Chandler, K.; Eudy, L.
2007-03-01
This report provides an evaluation of three prototype fuel cell-powered transit buses operating at AC Transit in Oakland, California, and six baseline diesel buses similar in design to the fuel cell buses.
NASA Astrophysics Data System (ADS)
Marec, J. P.
Techniques for the optimization (in terms of minimal mass loss) of spacecraft trajectories are developed. The optimal transfer is defined; a model of the propulsion system is presented; the two-impulse Hohmann transfer between coplanar circular orbits is shown to be the optimal trajectory for that case; and the problems of optimal transfer in general, uniform, and central gravitational fields are analyzed. A number of specific cases are examined and illustrated with diagrams and graphs.
Testing Transition State Theory on Kac-Zwanzig Model
NASA Astrophysics Data System (ADS)
Ariel, G.; vanden-Eijnden, E.
2007-01-01
A variant of the Kac-Zwanzig model is used to test the prediction of transition state theory (TST) and variational transition state theory (VTST). The model describes the evolution of a distinguished particle moving in a double-well external potential and coupled to N free particles through linear springs. While the Kac-Zwanzig model is deterministic, under appropriate choice of the model parameters the evolution of the distinguished particle can be approximated by a two-state Markov chain whose transition rate constants can be computed exactly in suitable limit. Here, these transition rate constants are compared with the predictions of TST and VTST. It is shown that the application of TST with a naive (albeit natural) choice of dividing surface leads to the wrong prediction of the transition rate constants. This is due to crossings of the dividing surface that do not correspond to actual transition events. However, optimizing over the dividing surface within VTST allows one to eliminate completely these spurious crossings, and therefore derive the correct transition rate constants for the model. The reasons why VTST is successful in this model are discussed, which allows one to speculate on the reliability of VTST in more complicated systems.
Optimally controlling the human connectome: the role of network topology
Betzel, Richard F.; Gu, Shi; Medaglia, John D.; Pasqualetti, Fabio; Bassett, Danielle S.
2016-01-01
To meet ongoing cognitive demands, the human brain must seamlessly transition from one brain state to another, in the process drawing on different cognitive systems. How does the brain’s network of anatomical connections help facilitate such transitions? Which features of this network contribute to making one transition easy and another transition difficult? Here, we address these questions using network control theory. We calculate the optimal input signals to drive the brain to and from states dominated by different cognitive systems. The input signals allow us to assess the contributions made by different brain regions. We show that such contributions, which we measure as energy, are correlated with regions’ weighted degrees. We also show that the network communicability, a measure of direct and indirect connectedness between brain regions, predicts the extent to which brain regions compensate when input to another region is suppressed. Finally, we identify optimal states in which the brain should start (and finish) in order to minimize transition energy. We show that the optimal target states display high activity in hub regions, implicating the brain’s rich club. Furthermore, when rich club organization is destroyed, the energy cost associated with state transitions increases significantly, demonstrating that it is the richness of brain regions that makes them ideal targets. PMID:27468904
Optimally controlling the human connectome: the role of network topology.
Betzel, Richard F; Gu, Shi; Medaglia, John D; Pasqualetti, Fabio; Bassett, Danielle S
2016-01-01
To meet ongoing cognitive demands, the human brain must seamlessly transition from one brain state to another, in the process drawing on different cognitive systems. How does the brain's network of anatomical connections help facilitate such transitions? Which features of this network contribute to making one transition easy and another transition difficult? Here, we address these questions using network control theory. We calculate the optimal input signals to drive the brain to and from states dominated by different cognitive systems. The input signals allow us to assess the contributions made by different brain regions. We show that such contributions, which we measure as energy, are correlated with regions' weighted degrees. We also show that the network communicability, a measure of direct and indirect connectedness between brain regions, predicts the extent to which brain regions compensate when input to another region is suppressed. Finally, we identify optimal states in which the brain should start (and finish) in order to minimize transition energy. We show that the optimal target states display high activity in hub regions, implicating the brain's rich club. Furthermore, when rich club organization is destroyed, the energy cost associated with state transitions increases significantly, demonstrating that it is the richness of brain regions that makes them ideal targets. PMID:27468904
Salinas, Daniel; Baker, David P
2015-01-01
Objective Previous studies found that developed and developing countries present opposite education-overweight gradients but have not considered the dynamics at different levels of national development. A U-inverted curve is hypothesized to best describe the education-overweight association. It is also hypothesized that as the nutrition transition unfolds within nations the shape of education-overweight curve change. Design Multi-level logistic regression estimates the moderating effect of the nutrition transition at the population level on education-overweight gradient. At the individual level, a non-linear estimate of the education association assesses the optimal functional form of the association across the nutrition transition. Setting Twenty-two administrations of the Demographic and Health Survey, collected at different time points across the nutrition transition in nine Latin American/Caribbean countries. Subjects Mothers of reproductive age (15–49) in each administration (n 143,258). Results In the pooled sample, a non-linear education gradient on mothers‘ overweight is found; each additional year of schooling increases the probability of being overweight up to the end of primary schooling, after which each additional year of schooling decreases the probability of overweight. Also, as access to diets of high animal fats and sweeteners increases over time, the curve‘s critical point moves to lower education levels, the detrimental positive effect of education diminishes, and both occur as the overall risk of overweight increases with greater access to harmful diets. Conclusions Both hypotheses are supported. As the nutrition transition progresses, the education-overweight curve steadily shifts to a negative linear association with higher average risk of overweight; and education, at increasingly lower levels, acts as a “social vaccine” against increasing risk of overweight. These empirical patterns fit the general “population education
Converging towards the optimal path to extinction
Schwartz, Ira B.; Forgoston, Eric; Bianco, Simone; Shaw, Leah B.
2011-01-01
Extinction appears ubiquitously in many fields, including chemical reactions, population biology, evolution and epidemiology. Even though extinction as a random process is a rare event, its occurrence is observed in large finite populations. Extinction occurs when fluctuations owing to random transitions act as an effective force that drives one or more components or species to vanish. Although there are many random paths to an extinct state, there is an optimal path that maximizes the probability to extinction. In this paper, we show that the optimal path is associated with the dynamical systems idea of having maximum sensitive dependence to initial conditions. Using the equivalence between the sensitive dependence and the path to extinction, we show that the dynamical systems picture of extinction evolves naturally towards the optimal path in several stochastic models of epidemics. PMID:21571943
Ornithopter transition trajectories
NASA Astrophysics Data System (ADS)
Dietl, John M.; Garcia, Ephrahim
2010-04-01
The design of stable trim conditions for forward flight and for hover has been achieved. In forward flight, an ornithopter is configured like a conventional airplane or large bird. Its fuselage is essentially horizontal and the wings heave in a vertical plane. In hover, however, the body pitches vertically so that the wing stroke in the horizontal plane. Thrust directed downward, the vehicle remains aloft while the downdraft envelops the tail to provide enough flow for vehicle control and stabilization. To connect these trajectories dynamically is the goal. The naïve approach-to choose two stable trajectories and switch between them-has been accomplished. A new approach is to establish an open-loop trajectory through a trajectory optimization algorithm-optimized for shortest altitude drop, shortest stopping distance, or lowest energy consumption.
Transition Metal Switchable Mirror
2009-08-21
The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.
NASA Astrophysics Data System (ADS)
Friedman, S. R.; Khalil, M.; Taborek, P.
2013-11-01
Optical images were used to study the wetting behavior of water on graphite, sapphire, and quartz along the liquid vapor coexistence curve from room temperature to 300°C. Wetting transitions were identified by the temperature at which the contact angle decreased to zero and also by the disappearance of dropwise condensation. These two methods yielded consistent values for the wetting temperatures, which were 185°C, 234°C, and 271°C for water on quartz, sapphire, and graphite, respectively. We compare our results with the theoretical predictions based on a simplified model of the water-substrate potential and sharp interfaces.
Friedman, S R; Khalil, M; Taborek, P
2013-11-27
Optical images were used to study the wetting behavior of water on graphite, sapphire, and quartz along the liquid vapor coexistence curve from room temperature to 300 °C. Wetting transitions were identified by the temperature at which the contact angle decreased to zero and also by the disappearance of dropwise condensation. These two methods yielded consistent values for the wetting temperatures, which were 185 °C, 234 °C, and 271 °C for water on quartz, sapphire, and graphite, respectively. We compare our results with the theoretical predictions based on a simplified model of the water-substrate potential and sharp interfaces.
Transition Metal Switchable Mirror
None
2016-07-12
The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm
Transition Metal Switchable Mirror
None
2016-07-12
The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.
MINEHOUND: transition to production
NASA Astrophysics Data System (ADS)
Daniels, David J.; Curtis, Paul; Hunt, Nigel; Braunstein, Jürgen; Merz, Armin
2007-04-01
The UK Department for International Development (DfID), in collaboration with the German Foreign Ministry (Auswärtiges Amt), contracted ERA Technology to carry out extensive field trials in Cambodia, Bosnia and Angola of an advanced technology, dual sensor, and hand-held landmine detector system called MINEHOUND TM. This detector combines a metal detector with a Ground Penetrating Radar (GPR). As a result of extremely successful trials MINEHOUND TM was developed as a product by ERA Technology and Vallon GmbH and has been available for sale since late 2006. This paper describes the transition to production of the detector.
Electromagnetic transitions in hypernuclei
Chrien, R.E.
1986-01-01
The object of this review is to survey observations of electromagnetic transitions in hypernuclei and to point out contributions of these observations to an understanding of the effective two-body hyperon-nucleon forces in the nucleus. The discussion concentrates on lambda-hyperon nucleon potentials. Future plans for high resolution hypernuclear spectroscopy using Ge diode detectors is discussed, especially regarding the window of utility of such devices. Expected improvements in beam facilities are also reviewed. 9 refs., 4 figs., 1 tab. (DWL)
Transition in Turner's syndrome.
Saenger, Paul
2004-06-01
Management of the chromosomal condition Turner's syndrome requires consistent medical care, especially during the time when affected girls transition from childhood into adulthood. The medical problems that first develop during childhood of a patient with Turner's syndrome such as congenital heart disease, hearing loss, skeletal problems and dental and ophthalmological abnormalities, should be followed into adulthood. Providing the necessary continuum of care will require that medical centers develop teams with the appropriate expertise in treatment of Turner's syndrome. Now more than ever patients with Turner's syndrome have the capability of achieving their full potential, but it requires a multidisciplinary approach toward care throughout their lifetime.
Nies, Dietrich H; Grass, Gregor
2009-08-01
This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing only a minor role. If these systems do not provide sufficient amounts of a needed ion to the cell, genes for ATP-hydrolyzing high-affinity but low-rate uptake systems are induced, e.g., ABC transport systems or P-type ATPases. On the other hand, if the amount of an ion is in surplus, genes for efflux systems are induced. By combining different kinds of uptake and efflux systems with regulation at the levels of gene expression and transport activity, the concentration of a single ion in the cytoplasm and the composition of the cellular ion "bouquet" can be rapidly adjusted and carefully controlled. The toxicity threshold of an ion is defined by its ability to produce radicals (copper, iron, chromate), to bind to sulfide and thiol groups (copper, zinc, all cations of the second and third transition period), or to interfere with the metabolism of other ions. Iron poses an exceptional metabolic problem due its metabolic importance and the low solubility of Fe(III) compounds, combined with the ability to cause dangerous Fenton reactions. This dilemma for the cells led to the evolution of sophisticated multi-channel iron uptake and storage pathways to prevent the occurrence of unbound iron in the cytoplasm. Toxic metals like Cd2+ bind to thiols and sulfide, preventing assembly of iron complexes and releasing the metal from iron-sulfur clusters. In the unique case of mercury, the
Pivotal Transitions - Historical and Today
NASA Astrophysics Data System (ADS)
Hurley, M.
2008-08-01
The goal of this paper is to enable readers to better "design" successful transitions that move Science and Technology or Research and Development (S&T/R&D) technologies and systems into operational capabilities for users. Transitions from S&T/R&D into acquisition and operations are challenging and critical to providing capab ilities to end users. Two historical examples, the Global Positioning System (GPS) and the Disaster Monitoring Constellation (DMC), are explored. Two current examples are also explored, including one from Operationally Responsive Space (ORS) which is in th e early stages of transition. While transitions are necessary, transition periods are inherently challenging and dynamically changing situations. These situations must be carefully managed and led in order to succeed. Characteristics, approaches, and incentives that foster effective transitions are discussed. Understanding the transition process and the communities involved allows one to maximize the chance of successfully moving an S&T/R&D development into an operational capability supporting end users.
Optimizing photosynthesis under fluctuating light
Pesaresi, Paolo; Hertle, Alexander; Pribi, Mathias; Schneider, Anja; Kleine, Tatjana
2010-01-01
Optimal photosynthetic performance requires that equal amounts of light are absorbed by photosystem ii (PSii) and photosystem i (PSi), which are functionally linked through the photosynthetic electron transport chain. However, photosynthetic organisms must cope with light conditions that lead to the preferential stimulation of one or the other of the photosystems. Plants react to such imbalances by mounting acclimation responses that redistribute excitation energy between photosystems and restore the photosynthetic redox poise. in the short term, this involves the so-called state transition process, which, over periods of minutes, alters the antennal crosssections of the photosystems through the reversible association of a mobile fraction of light-harvesting complex ii (LHCii) with PSi or PSii. Longer-lasting changes in light quality initiate a long-term response (LTr), occurring on a timescale of hours to days, that redresses imbalances in excitation energy by changing the relative amounts of the two photosystems. Despite the differences in their timescales of action, state transitions and LTr are both triggered by the redox state of the plastoquinone (PQ) pool, via the activation of the thylakoid kinase STN7, which appears to act as a common redox sensor and/or signal transducer for both responses. This review highlights recent findings concerning the role of STN7 in coordinating short- and long-term photosynthetic acclimation responses. PMID:20592803
McGuire-Snieckus, Rebecca
2014-04-01
Optimism is generally accepted by psychiatrists, psychologists and other caring professionals as a feature of mental health. Interventions typically rely on cognitive-behavioural tools to encourage individuals to 'stop negative thought cycles' and to 'challenge unhelpful thoughts'. However, evidence suggests that most individuals have persistent biases of optimism and that excessive optimism is not conducive to mental health. How helpful is it to facilitate optimism in individuals who are likely to exhibit biases of optimism already? By locating the cause of distress at the individual level and 'unhelpful' cognitions, does this minimise wider systemic social and economic influences on mental health?
Mikhalevich, V.S.; Sergienko, I.V.; Zadiraka, V.K.; Babich, M.D.
1994-11-01
This article examines some topics of optimization of computations, which have been discussed at 25 seminar-schools and symposia organized by the V.M. Glushkov Institute of Cybernetics of the Ukrainian Academy of Sciences since 1969. We describe the main directions in the development of computational mathematics and present some of our own results that reflect a certain design conception of speed-optimal and accuracy-optimal (or nearly optimal) algorithms for various classes of problems, as well as a certain approach to optimization of computer computations.
McGuire-Snieckus, Rebecca
2014-01-01
Optimism is generally accepted by psychiatrists, psychologists and other caring professionals as a feature of mental health. Interventions typically rely on cognitive-behavioural tools to encourage individuals to ‘stop negative thought cycles’ and to ‘challenge unhelpful thoughts’. However, evidence suggests that most individuals have persistent biases of optimism and that excessive optimism is not conducive to mental health. How helpful is it to facilitate optimism in individuals who are likely to exhibit biases of optimism already? By locating the cause of distress at the individual level and ‘unhelpful’ cognitions, does this minimise wider systemic social and economic influences on mental health? PMID:25237497
Optimal driving of Bose-Einstein condensates in optical cavities
Caneva, T.; Calarco, T.; Montangero, S.
2014-12-04
We apply quantum optimal control to enhance the performance of the experimental setup of Ref. [1], speeding up the system dynamics at time scales of the order of the quantum speed limit. We perform a fast crossing of the quantum phase transition the system undergoes under realistic experimental conditions, and we present a new scaling-based strategy to compute optimal pulses for systems at the thermodynamical limit.
Heuristic optimization of the scanning path of particle therapy beams
Pardo, J.; Donetti, M.; Bourhaleb, F.; Ansarinejad, A.; Attili, A.; Cirio, R.; Garella, M. A.; Giordanengo, S.; Givehchi, N.; La Rosa, A.; Marchetto, F.; Monaco, V.; Pecka, A.; Peroni, C.; Russo, G.; Sacchi, R.
2009-06-15
Quasidiscrete scanning is a delivery strategy for proton and ion beam therapy in which the beam is turned off when a slice is finished and a new energy must be set but not during the scanning between consecutive spots. Different scanning paths lead to different dose distributions due to the contribution of the unintended transit dose between spots. In this work an algorithm to optimize the scanning path for quasidiscrete scanned beams is presented. The classical simulated annealing algorithm is used. It is a heuristic algorithm frequently used in combinatorial optimization problems, which allows us to obtain nearly optimal solutions in acceptable running times. A study focused on the best choice of operational parameters on which the algorithm performance depends is presented. The convergence properties of the algorithm have been further improved by using the next-neighbor algorithm to generate the starting paths. Scanning paths for two clinical treatments have been optimized. The optimized paths are found to be shorter than the back-and-forth, top-to-bottom (zigzag) paths generally provided by the treatment planning systems. The gamma method has been applied to quantify the improvement achieved on the dose distribution. Results show a reduction of the transit dose when the optimized paths are used. The benefit is clear especially when the fluence per spot is low, as in the case of repainting. The minimization of the transit dose can potentially allow the use of higher beam intensities, thus decreasing the treatment time. The algorithm implemented for this work can optimize efficiently the scanning path of quasidiscrete scanned particle beams. Optimized scanning paths decrease the transit dose and lead to better dose distributions.
Optimization of parameterized lightpipes
NASA Astrophysics Data System (ADS)
Koshel, R. John
2007-01-01
Parameterization via the bend locus curve allows optimization of single-spherical-bend lightpipes. It takes into account the bend radii, the bend ratio, allowable volume, thickness, and other terms. Parameterization of the lightpipe allows the inclusion of a constrained optimizer to maximize performance of the lightpipe. The simplex method is used for optimization. The standard and optimal simplex methods are used to maximize the standard Lambertian transmission of the lightpipe. A second case presents analogous results when the ray-sample weighted, peak-to-average irradiance uniformity is included with the static Lambertian transmission. These results are compared to a study of the constrained merit space. Results show that both optimizers can locate the optimal solution, but the optimal simplex method accomplishes such with a reduced number of ray-trace evaluations.
NASA Technical Reports Server (NTRS)
Venter, Gerhard; Sobieszczanski-Sobieski Jaroslaw
2002-01-01
The purpose of this paper is to show how the search algorithm known as particle swarm optimization performs. Here, particle swarm optimization is applied to structural design problems, but the method has a much wider range of possible applications. The paper's new contributions are improvements to the particle swarm optimization algorithm and conclusions and recommendations as to the utility of the algorithm, Results of numerical experiments for both continuous and discrete applications are presented in the paper. The results indicate that the particle swarm optimization algorithm does locate the constrained minimum design in continuous applications with very good precision, albeit at a much higher computational cost than that of a typical gradient based optimizer. However, the true potential of particle swarm optimization is primarily in applications with discrete and/or discontinuous functions and variables. Additionally, particle swarm optimization has the potential of efficient computation with very large numbers of concurrently operating processors.
Integrated controls design optimization
Lou, Xinsheng; Neuschaefer, Carl H.
2015-09-01
A control system (207) for optimizing a chemical looping process of a power plant includes an optimizer (420), an income algorithm (230) and a cost algorithm (225) and a chemical looping process models. The process models are used to predict the process outputs from process input variables. Some of the process in puts and output variables are related to the income of the plant; and some others are related to the cost of the plant operations. The income algorithm (230) provides an income input to the optimizer (420) based on a plurality of input parameters (215) of the power plant. The cost algorithm (225) provides a cost input to the optimizer (420) based on a plurality of output parameters (220) of the power plant. The optimizer (420) determines an optimized operating parameter solution based on at least one of the income input and the cost input, and supplies the optimized operating parameter solution to the power plant.
Graves, C.E.
1994-08-31
The preparation for decontamination and decommissioning (transition) of the 309 Building is projected to be completed by the end of the fiscal year (FY) 1998. The major stabilization and decontamination efforts include the Plutonium Recycle Test Reactor (PRTR), fuel storage and transfer pits, Transfer Waste (TW) tanks and the Ion Exchange Vaults. In addition to stabilizing contaminated areas, equipment, components, records, waste products, etc., will be dispositioned. All nonessential systems, i.e., heating, ventilation, and air conditioning (HVAC), electrical, monitoring, fluids, etc., will be shut down and drained/de-energized. This will allow securing of the process, laboratory, and office areas of the facility. After that, the facility will be operated at a level commensurate with its surveillance needs while awaiting D&D. The implementation costs for FY 1995 through FY 1998 for the transition activities are estimated to be $1,070K, $2,115K, $2,939K, and $4,762K, respectively. Costs include an assumed company overhead of 20% and a 30% out year contingency.
Planet Demographics from Transits
NASA Astrophysics Data System (ADS)
Howard, Andrew
2015-08-01
From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.
High pressure phase transition and elastic properties of americium telluride
NASA Astrophysics Data System (ADS)
Aynyas, Mahendra; Rukmangad, Aditi; Arya, B. S.; Sanyal, S. P.
2013-06-01
The structural and elastic properties of Americium Telluride (AmTe) have been investigated by using a modified inter-ionic potential theory (MIPT). This theory is capable of explaining first order phase transition with a crystallographic change NaCl to CsCl structure for this compound. The values of optimized lattice constant, phase transition pressure, zero pressure bulk modulus and second order elastic constants (C11, C44) agree well with their corresponding experimental data. Debye temperature (θD) is also calculated for this compound for the first time.
Approximating random quantum optimization problems
NASA Astrophysics Data System (ADS)
Hsu, B.; Laumann, C. R.; Läuchli, A. M.; Moessner, R.; Sondhi, S. L.
2013-06-01
We report a cluster of results regarding the difficulty of finding approximate ground states to typical instances of the quantum satisfiability problem k-body quantum satisfiability (k-QSAT) on large random graphs. As an approximation strategy, we optimize the solution space over “classical” product states, which in turn introduces a novel autonomous classical optimization problem, PSAT, over a space of continuous degrees of freedom rather than discrete bits. Our central results are (i) the derivation of a set of bounds and approximations in various limits of the problem, several of which we believe may be amenable to a rigorous treatment; (ii) a demonstration that an approximation based on a greedy algorithm borrowed from the study of frustrated magnetism performs well over a wide range in parameter space, and its performance reflects the structure of the solution space of random k-QSAT. Simulated annealing exhibits metastability in similar “hard” regions of parameter space; and (iii) a generalization of belief propagation algorithms introduced for classical problems to the case of continuous spins. This yields both approximate solutions, as well as insights into the free energy “landscape” of the approximation problem, including a so-called dynamical transition near the satisfiability threshold. Taken together, these results allow us to elucidate the phase diagram of random k-QSAT in a two-dimensional energy-density-clause-density space.
Gait transition cost in humans.
Usherwood, James R; Bertram, John E A
2003-11-01
The energetics of locomotion depend largely on speed, gait and body size. Gait selection for a given speed appears partly, but perhaps not wholly, related to metabolic cost. One cost normally omitted from considerations of locomotion efficiency is the metabolic cost of the transition between gaits. We present the first direct assessment of the metabolic cost for the walk-run/run-walk transition in humans. The average increase in metabolic cost for a step involving a transition is 1.75 times that of a mean non-transition step at a speed where metabolic power requirements are identical for walking and running. Despite this substantial increase in cost for the transition step, the metabolic cost of gait transition is unlikely to have a strong bearing on the process of gait selection as the cost of using a metabolically inappropriate gait, even for only a few steps, will dominate. PMID:14564525
Symmetry in DIET phase transitions
NASA Astrophysics Data System (ADS)
Zhang, J. P.; Marks, L. D.
1989-11-01
Analysis of the route of the phase transitions in transition metal oxides driven by DIET of oxygen from the surfaces observed by high resolution electron microscopy indicates that there is a symmetry selection rule. The phase transitions are to a structure with a higher point group symmetry where the new phase with a lower oxygen content is either one with a supergroup symmetry with respect to the original phase, or is an amorphous intermediary. The final phase has the highest symmetry and is also a metallic conductor. If a possible lower oxygen content phase does not have the correct supergroup symmetry, it is not formed. It is also found that the point group is conserved during the phase transition if the oxide belongs to the highest groups O h or D 6h. This symmetry selection rule can therefore be used to predict the route of the phase transition. The symmetry rule operates when the phase transition is diffusional.
Bott, G; Barnard, J; Prior, K
2015-01-01
Operation GRITROCK saw the first operational deployment of the Maritime In Transit Care team from the Role 2 (Enhanced) (R2(E)) Medical Treatment Facility, which is able to provide Damage Control Surgery and the limited holding of patients, situated on board RFA ARGUS. Whilst the Medical Emergency Response Team demonstrated the capability of advanced military Pre-Hospital Emergency Care (PHEC) on Op HERRICK, the need to provide a similar high level of care on contingency operations was recognised. Op GRITROCK allowed for the continued exploration of a maritime capability from an established R2(E) platform whilst providing medical evacuation capability for a significant population at risk distributed over a large Joint Operation Area. Although the patient load during the operation was low, key lessons were learnt and opportunities identified to further develop the newly recognised sub-speciality of PHEC, both medically and logistically, and these will be discussed in this article. PMID:26867404
NASA Technical Reports Server (NTRS)
Viterna, Larry A.
1997-01-01
A government, industry, and university cooperative is developing an advanced hybrid electric city transit bus. Goals of this effort include doubling the fuel economy compared to current buses and reducing emissions to one-tenth of current EPA standards. Unique aspects of the vehicle's power system include the use of ultra-capacitors as an energy storage system, and a planned natural gas fueled turbogenerator developed from a small jet engine. Power from both the generator and energy storage system is provided to a variable speed electric motor attached to the rear axle. At over 15000 kg gross weight, this is the largest vehicle of its kind ever built using ultra-capacitor energy storage. This paper describes the overall power system architecture, the evolution of the control strategy, and its performance over industry standard drive cycles.
Nonadiabatic transition path sampling
NASA Astrophysics Data System (ADS)
Sherman, M. C.; Corcelli, S. A.
2016-07-01
Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.
Supercomputer optimizations for stochastic optimal control applications
NASA Technical Reports Server (NTRS)
Chung, Siu-Leung; Hanson, Floyd B.; Xu, Huihuang
1991-01-01
Supercomputer optimizations for a computational method of solving stochastic, multibody, dynamic programming problems are presented. The computational method is valid for a general class of optimal control problems that are nonlinear, multibody dynamical systems, perturbed by general Markov noise in continuous time, i.e., nonsmooth Gaussian as well as jump Poisson random white noise. Optimization techniques for vector multiprocessors or vectorizing supercomputers include advanced data structures, loop restructuring, loop collapsing, blocking, and compiler directives. These advanced computing techniques and superconducting hardware help alleviate Bellman's curse of dimensionality in dynamic programming computations, by permitting the solution of large multibody problems. Possible applications include lumped flight dynamics models for uncertain environments, such as large scale and background random aerospace fluctuations.
Wheeler, Ward C
2003-08-01
The problem of determining the minimum cost hypothetical ancestral sequences for a given cladogram is known to be NP-complete (Wang and Jiang, 1994). Traditionally, point estimations of hypothetical ancestral sequences have been used to gain heuristic, upper bounds on cladogram cost. These include procedures with such diverse approaches as non-additive optimization of multiple sequence alignment, direct optimization (Wheeler, 1996), and fixed-state character optimization (Wheeler, 1999). A method is proposed here which, by extending fixed-state character optimization, replaces the estimation process with a search. This form of optimization examines a diversity of potential state solutions for cost-efficient hypothetical ancestral sequences and can result in greatly more parsimonious cladograms. Additionally, such an approach can be applied to other NP-complete phylogenetic optimization problems such as genomic break-point analysis. PMID:14531408
NASA Technical Reports Server (NTRS)
Wheeler, Ward C.
2003-01-01
The problem of determining the minimum cost hypothetical ancestral sequences for a given cladogram is known to be NP-complete (Wang and Jiang, 1994). Traditionally, point estimations of hypothetical ancestral sequences have been used to gain heuristic, upper bounds on cladogram cost. These include procedures with such diverse approaches as non-additive optimization of multiple sequence alignment, direct optimization (Wheeler, 1996), and fixed-state character optimization (Wheeler, 1999). A method is proposed here which, by extending fixed-state character optimization, replaces the estimation process with a search. This form of optimization examines a diversity of potential state solutions for cost-efficient hypothetical ancestral sequences and can result in greatly more parsimonious cladograms. Additionally, such an approach can be applied to other NP-complete phylogenetic optimization problems such as genomic break-point analysis. c2003 The Willi Hennig Society. Published by Elsevier Science (USA). All rights reserved.
Analog neural nonderivative optimizers.
Teixeira, M M; Zak, S H
1998-01-01
Continuous-time neural networks for solving convex nonlinear unconstrained programming problems without using gradient information of the objective function are proposed and analyzed. Thus, the proposed networks are nonderivative optimizers. First, networks for optimizing objective functions of one variable are discussed. Then, an existing one-dimensional optimizer is analyzed, and a new line search optimizer is proposed. It is shown that the proposed optimizer network is robust in the sense that it has disturbance rejection property. The network can be implemented easily in hardware using standard circuit elements. The one-dimensional net is used as a building block in multidimensional networks for optimizing objective functions of several variables. The multidimensional nets implement a continuous version of the coordinate descent method.
Zhou, Zhi; de Bedout, Juan Manuel; Kern, John Michael; Biyik, Emrah; Chandra, Ramu Sharat
2013-01-22
A system for optimizing customer utility usage in a utility network of customer sites, each having one or more utility devices, where customer site is communicated between each of the customer sites and an optimization server having software for optimizing customer utility usage over one or more networks, including private and public networks. A customer site model for each of the customer sites is generated based upon the customer site information, and the customer utility usage is optimized based upon the customer site information and the customer site model. The optimization server can be hosted by an external source or within the customer site. In addition, the optimization processing can be partitioned between the customer site and an external source.
Sharp transitions in low-number quantum dots Bayesian magnetometry
Mazurek, Paweł; Horodecki, Michał; Czekaj, Łukasz; Horodecki, Paweł
2016-01-01
We consider Bayesian estimate of static magnetic field, characterized by a prior Gaussian probability distribution, in systems of a few electron quantum dot spins interacting with infinite temperature spin environment via hyperfine interaction. Sudden transitions among optimal states and measurements are observed. Usefulness of measuring occupation levels is shown for all times of the evolution, together with the role of entanglement in the optimal scenario. For low values of magnetic field, memory effects stemming from the interaction with environment provide limited metrological advantage. PMID:27686417
Homotopy optimization methods for global optimization.
Dunlavy, Daniel M.; O'Leary, Dianne P. (University of Maryland, College Park, MD)
2005-12-01
We define a new method for global optimization, the Homotopy Optimization Method (HOM). This method differs from previous homotopy and continuation methods in that its aim is to find a minimizer for each of a set of values of the homotopy parameter, rather than to follow a path of minimizers. We define a second method, called HOPE, by allowing HOM to follow an ensemble of points obtained by perturbation of previous ones. We relate this new method to standard methods such as simulated annealing and show under what circumstances it is superior. We present results of extensive numerical experiments demonstrating performance of HOM and HOPE.
Structural optimization using optimality criteria methods
NASA Technical Reports Server (NTRS)
Khot, N. S.; Berke, L.
1984-01-01
Optimality criteria methods take advantage of some concepts as those of statically determinate or indeterminate structures, and certain variational principles of structural dynamics, to develop efficient algorithms for the sizing of structures that are subjected to stiffness-related constraints. Some of the methods and iterative strategies developed over the last decade for calculations of the Lagrange multipliers in stressand displacement-limited problems, as well as for satisfying the appropriate optimality criterion, are discussed. The application of these methods are illustrated by solving problems with stress and displacement constraints.
Transit satellite system timing capabilities
NASA Technical Reports Server (NTRS)
Finsod, T. D.
1978-01-01
Current time transfer capabilities of the Transit Satellite System are reviewed. Potential improvements in the changes in equipment and operational procedures using operational satellites are discussed.
Transit administration and planning research
de Corla-Souza; Gupta.
1989-01-01
The 10 papers in the report deal with the following areas: Evaluation of demand-management strategies for Toledo's year 2010 transportation plan; Accommodating deaf and hard-of-hearing persons on public transportation systems in Massachusetts; Quick approach to compare highway and bus transit alternatives using the arterial analysis package; Panel survey approach to measuring transit route service elasticity of demand; UMTA and major investments: evaluation process and results; Using early performance to project transit route ridership: comparison of methods; Institutional requirements for competition: labor issues; Updating ride checks with multiple point checks; Producing section 15 service-consumed data: challenge for large transit; Parkrose targeted marketing campaign pass-incentive program.
Quantum phase transition in space
Damski, Bogdan; Zurek, Wojciech H
2008-01-01
A quantum phase transition between the symmetric (polar) phase and the phase with broken symmetry can be induced in a ferromagnetic spin-1 Bose-Einstein condensate in space (rather than in time). We consider such a phase transition and show that the transition region in the vicinity of the critical point exhibits scalings that reflect a compromise between the rate at which the transition is imposed (i.e., the gradient of the control parameter) and the scaling of the divergent healing length in the critical region. Our results suggest a method for the direct measurement of the scaling exponent {nu}.
Conceptual design optimization study
NASA Technical Reports Server (NTRS)
Hollowell, S. J.; Beeman, E. R., II; Hiyama, R. M.
1990-01-01
The feasibility of applying multilevel functional decomposition and optimization techniques to conceptual design of advanced fighter aircraft was investigated. Applying the functional decomposition techniques to the conceptual design phase appears to be feasible. The initial implementation of the modified design process will optimize wing design variables. A hybrid approach, combining functional decomposition techniques for generation of aerodynamic and mass properties linear sensitivity derivatives with existing techniques for sizing mission performance and optimization, is proposed.
Smoothers for Optimization Problems
NASA Technical Reports Server (NTRS)
Arian, Eyal; Ta'asan, Shlomo
1996-01-01
We present a multigrid one-shot algorithm, and a smoothing analysis, for the numerical solution of optimal control problems which are governed by an elliptic PDE. The analysis provides a simple tool to determine a smoothing minimization process which is essential for multigrid application. Numerical results include optimal control of boundary data using different discretization schemes and an optimal shape design problem in 2D with Dirichlet boundary conditions.
Control and optimization system
Xinsheng, Lou
2013-02-12
A system for optimizing a power plant includes a chemical loop having an input for receiving an input parameter (270) and an output for outputting an output parameter (280), a control system operably connected to the chemical loop and having a multiple controller part (230) comprising a model-free controller. The control system receives the output parameter (280), optimizes the input parameter (270) based on the received output parameter (280), and outputs an optimized input parameter (270) to the input of the chemical loop to control a process of the chemical loop in an optimized manner.
Essentials of Transition Planning. Brookes Transition to Adulthood Series
ERIC Educational Resources Information Center
Wehman, Paul
2011-01-01
For young people with disabilities, crossing the bridge to adulthood will be empowering instead of intimidating--when their support teams know the essentials of effective transition planning. Now all the fundamentals of well-crafted transition plans are collected in one concise quick-guide, straight from one of the top authorities on helping young…
Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Preliminary Evaluation Results
Chandler, K.; Eudy, L.
2008-10-01
This report provides preliminary results from a National Renewable Energy Laboratory evaluation of a protoptye fuel cell transit bus operating at Connecticut Transit in Hartford. Included are descriptions of the planned fuel cell bus demonstration and equipment; early results and agency experience are also provided.
Light Scattering in Exoplanet Transits
NASA Astrophysics Data System (ADS)
Robinson, Tyler D.; Fortney, Jonathan J.
2016-10-01
Transit spectroscopy is currently the leading technique for studying exoplanet atmospheric composition, and has led to the detection of molecular species, clouds, and/or hazes for numerous worlds outside the Solar System. The field of exoplanet transit spectroscopy will be revolutionized with the anticipated launch of NASA's James Webb Space Telescope (JWST) in 2018. Over the course of the design five year mission for JWST, the observatory is expected to provide in-depth observations of many tens of transiting exoplanets, including some worlds in the poorly understood 2–4 Earth-mass regime. As the quality of transit spectrum observations continues to improve, so should models of exoplanet transits. Thus, certain processes initially thought to be of second-order importance should be revisited and possibly added to modeling tools. For example, atmospheric refraction, which was commonly omitted from early transit spectrum models, has recently been shown to be of critical importance in some terrestrial exoplanet transits. Beyond refraction, another process that has seen little study with regards to exoplanet transits is light multiple scattering. In most cases, scattering opacity in exoplanet transits has been treated as equivalent to absorption opacity. However, this equivalence cannot always hold, such as in the case of a strongly forward scattering, weakly absorbing aerosol. In this presentation, we outline a theory of exoplanet transit spectroscopy that spans the geometric limit (used in most modern models) to a fully multiple scattering approach. We discuss a new technique for improving model efficiency that effectively separates photon paths, which tend to vary slowly in wavelength, from photon absorption, which can vary rapidly in wavelength. Using this newly developed approach, we explore situations where cloud or haze scattering may be important to JWST observations of gas giants, and comment on the conditions necessary for scattering to become a major
Rapid Mars transits with exhaust-modulated plasma propulsion
NASA Technical Reports Server (NTRS)
Chang-Diaz, Franklin R.; Braden, Ellen; Johnson, Ivan; Hsu, Michael M.; Yang, Tien Fang
1995-01-01
The operational characteristics of the Exhaust-Modulated Plasma Rocket are described. Four basic human and robotic mission scenarios to Mars are analyzed using numerical optimization techniques at variable specific impulse and constant power. The device is well suited for 'split-sprint' missions, allowing fast, one-way low-payload human transits of 90 to 104 days, as well as slower, 180-day, high-payload robotic precursor flights. Abort capabilities, essential for human missions, are also explored.
Detection by Transit Photometry
NASA Technical Reports Server (NTRS)
Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)
2002-01-01
A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.
Freezing Transition of Heteropolymers
NASA Astrophysics Data System (ADS)
Pande, Vijay Satyanand
1995-01-01
The ability to create synthetic heteropolymers with the protein-like capabilities of renaturation to a particular conformation capable of specific molecular recognition is of great technological importance. To create protein -like heteropolymers, we suggest "Imprinting," which dictates that monomers should be equilibrated at some low temperature prior to polymerization, then polymerized such that this monomer prearrangement is somewhat preserved. We argue that this optimization of monomers to themselves and to the target molecule prior to polymerization leads respectively to the protein-like properties of stability and functionality since the prearrangement of monomers is analogous to optimization performed by nature over evolutionary time. Thus, many of our results are applicable to proteins and may shed light on their biological and prebiological origins. To study Imprinting, we employ a variety of theoretical techniques. Since we must prove that the single heteropolymer conformation capable of specific molecular recognition dominates equilibrium, to computationally study the thermodynamics of Imprinted heteropolymers, we must enumerate every possible globular conformation; using a massively parallel supercomputer, we found the conformations in which the chains were polymerized were indeed the lowest energy conformation. We also validated Imprinting by the Monte Carlo kinetics of lattice models, thereby showing that the chains we proved to have the lowest energy conformations were able to kinetically access this conformation. Finally, we used replica mean field theory to examine the relationship between the nature of interactions chosen and the success of Imprinting by calculating the phase behavior for Imprinted heteropolymers directly from the microscopic Hamiltonian of monomer-monomer interactions; we have theoretically shown that Imprinting is feasible and indeed robust with respect to variations in several aspects, including the chemistry employed
Ant groups optimally amplify the effect of transiently informed individuals.
Gelblum, Aviram; Pinkoviezky, Itai; Fonio, Ehud; Ghosh, Abhijit; Gov, Nir; Feinerman, Ofer
2015-01-01
To cooperatively transport a large load, it is important that carriers conform in their efforts and align their forces. A downside of behavioural conformism is that it may decrease the group's responsiveness to external information. Combining experiment and theory, we show how ants optimize collective transport. On the single-ant scale, optimization stems from decision rules that balance individuality and compliance. Macroscopically, these rules poise the system at the transition between random walk and ballistic motion where the collective response to the steering of a single informed ant is maximized. We relate this peak in response to the divergence of susceptibility at a phase transition. Our theoretical models predict that the ant-load system can be transitioned through the critical point of this mesoscopic system by varying its size; we present experiments supporting these predictions. Our findings show that efficient group-level processes can arise from transient amplification of individual-based knowledge. PMID:26218613
Ant groups optimally amplify the effect of transiently informed individuals
Gelblum, Aviram; Pinkoviezky, Itai; Fonio, Ehud; Ghosh, Abhijit; Gov, Nir; Feinerman, Ofer
2015-01-01
To cooperatively transport a large load, it is important that carriers conform in their efforts and align their forces. A downside of behavioural conformism is that it may decrease the group's responsiveness to external information. Combining experiment and theory, we show how ants optimize collective transport. On the single-ant scale, optimization stems from decision rules that balance individuality and compliance. Macroscopically, these rules poise the system at the transition between random walk and ballistic motion where the collective response to the steering of a single informed ant is maximized. We relate this peak in response to the divergence of susceptibility at a phase transition. Our theoretical models predict that the ant-load system can be transitioned through the critical point of this mesoscopic system by varying its size; we present experiments supporting these predictions. Our findings show that efficient group-level processes can arise from transient amplification of individual-based knowledge. PMID:26218613
Ant groups optimally amplify the effect of transiently informed individuals
NASA Astrophysics Data System (ADS)
Gelblum, Aviram; Pinkoviezky, Itai; Fonio, Ehud; Ghosh, Abhijit; Gov, Nir; Feinerman, Ofer
2015-07-01
To cooperatively transport a large load, it is important that carriers conform in their efforts and align their forces. A downside of behavioural conformism is that it may decrease the group's responsiveness to external information. Combining experiment and theory, we show how ants optimize collective transport. On the single-ant scale, optimization stems from decision rules that balance individuality and compliance. Macroscopically, these rules poise the system at the transition between random walk and ballistic motion where the collective response to the steering of a single informed ant is maximized. We relate this peak in response to the divergence of susceptibility at a phase transition. Our theoretical models predict that the ant-load system can be transitioned through the critical point of this mesoscopic system by varying its size; we present experiments supporting these predictions. Our findings show that efficient group-level processes can arise from transient amplification of individual-based knowledge.
Case report: microcystic transitional cell carcinoma of the urinary bladder.
Radopoulos, Demetrios; Kalyvas, Konstantinos; Kotakidou, Rodi; Panagiotopoulou, Konstantina; Katsikas, Vasilios; Papathanasiou, Michalis
2005-01-01
We report a rare case of microcystic transitional cell carcinoma involving the urinary bladder, in a 38-year-old man, and we add our experience in the treatment of this neoplasm. The tumor was muscle invasive, and a radical cystectomy was performed. The patient received no postoperative chemotherapy or radiotherapy, and he has not signs of local recurrence or distal metastasis after 3 years of intense follow up. Even though the number of cases documented so far, is insufficient to draw safe conclusions regarding the optimal treatment of the microcystic variant of transitional cell carcinoma. Our case indicates that even in cases of microcystic transitional cell carcinoma with infiltrative nature, aggressive therapy is associated with good control of the disease locally and distally.
Projection of postgraduate students flow with a smoothing matrix transition diagram of Markov chain
NASA Astrophysics Data System (ADS)
Rahim, Rahela; Ibrahim, Haslinda; Adnan, Farah Adibah
2013-04-01
This paper presents a case study of modeling postgraduate students flow at the College of Art and Sciences, Universiti Utara Malaysia. First, full time postgraduate students and the semester they were in are identified. Then administrative data were used to estimate the transitions between these semesters for the year 2001-2005 periods. Markov chain model is developed to calculate the -5 and -10 years projection of postgraduate students flow at the college. The optimization question addressed in this study is 'Which transitions would sustain the desired structure in the dynamic situation such as trend towards graduation?' The smoothed transition probabilities are proposed to estimate the transition probabilities matrix of 16 × 16. The results shows that using smoothed transition probabilities, the projection number of postgraduate students enrolled in the respective semesters are closer to actual than using the conventional steady states transition probabilities.
MODEL UPDATING: TRANSITION FROM RESEARCH TO PRACTICE?
D. C. ZIMMERMAN; F. M. HEMEZ
2000-10-01
This session offers an open forum to discuss issues associated with the transition of nearly two decades of engineering research into computational guided model updating into industry state-of-the-practice. Related technical issues are the model updating technology, model reduction, test-analysis correlation and optimization strategies. The session is organized as follows. Technical presentations review the state-of-the-art in finite element model updating and present examples of industrial applications. The results of a recent survey on the potential and usefulness of the model updating technology are discussed. Panel discussions and interaction with the audience discuss industrial needs, future trends and challenges and why negative model updating results are never discussed within the structural dynamics community.
Transition-Independent Decentralized Markov Decision Processes
NASA Technical Reports Server (NTRS)
Becker, Raphen; Silberstein, Shlomo; Lesser, Victor; Goldman, Claudia V.; Morris, Robert (Technical Monitor)
2003-01-01
There has been substantial progress with formal models for sequential decision making by individual agents using the Markov decision process (MDP). However, similar treatment of multi-agent systems is lacking. A recent complexity result, showing that solving decentralized MDPs is NEXP-hard, provides a partial explanation. To overcome this complexity barrier, we identify a general class of transition-independent decentralized MDPs that is widely applicable. The class consists of independent collaborating agents that are tied up by a global reward function that depends on both of their histories. We present a novel algorithm for solving this class of problems and examine its properties. The result is the first effective technique to solve optimally a class of decentralized MDPs. This lays the foundation for further work in this area on both exact and approximate solutions.
Partnership Transitions and Maternal Parenting
ERIC Educational Resources Information Center
Beck, Audrey N.; Cooper, Carey E.; McLanahan, Sara; Brooks-Gunn, Jeanne
2010-01-01
We use data from the Fragile Families and Child Wellbeing Study (N = 1,975) to examine the association between mothers' partnership changes and parenting behavior during the first 5 years of their children's lives. We compare coresidential with dating transitions and recent with more distal transitions. We also examine interactions between…
Adult Transition Program without Walls
ERIC Educational Resources Information Center
Moberg, Eric
2010-01-01
Best practices in adult transition special education for moderate to severe students suggest student-centered planning that maximizes independence in adult life. Based on the above sources, school districts and governing boards would best serve moderate to severe transition special education students with increasing integration into the community…
Transition Planning for Foster Youth
ERIC Educational Resources Information Center
Geenen, Sarah J.; Powers, Laurie E.
2006-01-01
The study evaluated the IEPs/Individualized Transition Plans of 45 students who were in special education and foster care, and compared them to the plans of 45 students who were in special education only. Results indicate that the transition plans of foster youth with disabilities were poor in quality, both in absolute terms and in comparison to…
ERIC Educational Resources Information Center
ERIC Review, 1996
1996-01-01
The "ERIC Review" announces research results, publications, and new programs relevant to each issue's theme topic. This issue explores the topic of preparing young people to make the transition from school to work. The lead article by Ray D. Ryan and Susan Imel, "School-to-Work Transition: Genuine Reform or the Latest Fad?," summarizes…
Optimizing qubit phase estimation
NASA Astrophysics Data System (ADS)
Chapeau-Blondeau, François
2016-08-01
The theory of quantum state estimation is exploited here to investigate the most efficient strategies for this task, especially targeting a complete picture identifying optimal conditions in terms of Fisher information, quantum measurement, and associated estimator. The approach is specified to estimation of the phase of a qubit in a rotation around an arbitrary given axis, equivalent to estimating the phase of an arbitrary single-qubit quantum gate, both in noise-free and then in noisy conditions. In noise-free conditions, we establish the possibility of defining an optimal quantum probe, optimal quantum measurement, and optimal estimator together capable of achieving the ultimate best performance uniformly for any unknown phase. With arbitrary quantum noise, we show that in general the optimal solutions are phase dependent and require adaptive techniques for practical implementation. However, for the important case of the depolarizing noise, we again establish the possibility of a quantum probe, quantum measurement, and estimator uniformly optimal for any unknown phase. In this way, for qubit phase estimation, without and then with quantum noise, we characterize the phase-independent optimal solutions when they generally exist, and also identify the complementary conditions where the optimal solutions are phase dependent and only adaptively implementable.
Optimal Disturbances in Boundary Layers Subject to Streamwise Pressure Gradient
NASA Technical Reports Server (NTRS)
Tumin, Anatoli; Ashpis, David E.
2003-01-01
Laminar-turbulent transition in shear flows is still an enigma in the area of fluid mechanics. The conventional explanation of the phenomenon is based on the instability of the shear flow with respect to infinitesimal disturbances. The conventional hydrodynamic stability theory deals with the analysis of normal modes that might be unstable. The latter circumstance is accompanied by an exponential growth of the disturbances that might lead to laminar-turbulent transition. Nevertheless, in many cases, the transition scenario bypasses the exponential growth stage associated with the normal modes. This type of transition is called bypass transition. An understanding of the phenomenon has eluded us to this day. One possibility is that bypass transition is associated with so-called algebraic (non-modal) growth of disturbances in shear flows. In the present work, an analysis of the optimal disturbances/streamwise vortices associated with the transient growth mechanism is performed for boundary layers in the presence of a streamwise pressure gradient. The theory will provide the optimal spacing of the control elements in the spanwise direction and their placement in the streamwise direction.
Sampling diffusive transition paths
F. Miller III, Thomas; Predescu, Cristian
2006-10-12
We address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with sampling infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with sampling the coarse features of long paths. The fine-features sampling stiffness is eliminated with the use of the fast sampling algorithm (FSA), and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. We use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature.
Optimal Dynamics of Intermittent Water Supply
NASA Astrophysics Data System (ADS)
Lieb, Anna; Wilkening, Jon; Rycroft, Chris
2014-11-01
In many urban areas of the developing world, piped water is supplied only intermittently, as valves direct water to different parts of the water distribution system at different times. The flow is transient, and may transition between free-surface and pressurized, resulting in complex dynamical features with important consequences for water suppliers and users. These consequences include degradation of distribution system components, compromised water quality, and inequitable water availability. The goal of this work is to model the important dynamics and identify operating conditions that mitigate certain negative effects of intermittent water supply. Specifically, we will look at valve parameters occurring as boundary conditions in a network model of transient, transition flow through closed pipes. Optimization will be used to find boundary values to minimize pressure gradients and ensure equitable water availability.
Injection-locking optimization in unstable resonators.
Kedmi, J; Treves, D
1981-06-15
The problem of transverse-mode matching between the lowest-loss mode of a confocal unstable resonator and a Gaussian beam, which is injected into the resonator through a coupling hole in its back mirror, is analyzed. It is found that in resonators having equivalent Fresnel number >0.5, there is a value of the coupling hole diameter for which a mode transition occurs. Below this value the coupling coefficient between the mode and the injected signal increases with the hole diameter. The optimal coupling hole diameter for injection locking lies somewhat below the transition value, where the low-order mode is still dominant and the coupling coefficient is high (~0.25-0.30). The power loss through the coupling hole is negligible (~2%) compared to the output coupling, which is ~50-70%. PMID:20332894
Theory of antiferroelectric phase transitions
NASA Astrophysics Data System (ADS)
Tolédano, Pierre; Guennou, Mael
2016-07-01
At variance with structural ferroic phase transitions which give rise to macroscopic tensors coupled to macroscopic fields, criteria defining antiferroelectric (AFE) phase transitions are still under discussion due to the absence of specific symmetry properties characterizing their existence. They are recognized by the proximity of a ferroelectric (FE) phase induced under applied electric field, with a double hysteresis loop relating the induced polarization to the electric field and a typical anomaly of the dielectric permittivity. Here, we show that there exist indeed symmetry criteria defining AFE transitions. They relate the local symmetry of the polar crystallographic sites emerging at an AFE phase transition with the macroscopic symmetry of the AFE phase. The dielectric properties of AFE transitions are deduced from a Landau theoretical model in which ferroelectric and ferrielectric phases are shown to stabilize as the result of specific symmetry-allowed couplings of the AFE order parameter with the field-induced polarization.
Migraine and the menopausal transition.
Martin, Vincent T
2014-05-01
The menopausal transition or "perimenopause" represents a time period of turbulent changes in ovarian hormones as middle-aged women progress into menopause. The purpose of this article is to review the literature to determine the effect of the menopausal transition on migraine headaches and to develop a rational treatment approach to these patients. The menopausal transition is divided into early and stages based upon patterns of menstruation and specific reproductive hormones. Studies would suggest that the prevalence of migraine and other climacteric symptoms tend to peak during the late menopausal transition particularly in those with a past history of premenstrual stress disorder. Treatment approaches vary by stage of the menopausal transition and include conventional daily preventatives, mini-prophylaxis and hormonal therapies.
Optimal Limited Contingency Planning
NASA Technical Reports Server (NTRS)
Meuleau, Nicolas; Smith, David E.
2003-01-01
For a given problem, the optimal Markov policy over a finite horizon is a conditional plan containing a potentially large number of branches. However, there are applications where it is desirable to strictly limit the number of decision points and branches in a plan. This raises the question of how one goes about finding optimal plans containing only a limited number of branches. In this paper, we present an any-time algorithm for optimal k-contingency planning. It is the first optimal algorithm for limited contingency planning that is not an explicit enumeration of possible contingent plans. By modelling the problem as a partially observable Markov decision process, it implements the Bellman optimality principle and prunes the solution space. We present experimental results of applying this algorithm to some simple test cases.
Algorithms for bilevel optimization
NASA Technical Reports Server (NTRS)
Alexandrov, Natalia; Dennis, J. E., Jr.
1994-01-01
General multilevel nonlinear optimization problems arise in design of complex systems and can be used as a means of regularization for multi-criteria optimization problems. Here, for clarity in displaying our ideas, we restrict ourselves to general bi-level optimization problems, and we present two solution approaches. Both approaches use a trust-region globalization strategy, and they can be easily extended to handle the general multilevel problem. We make no convexity assumptions, but we do assume that the problem has a nondegenerate feasible set. We consider necessary optimality conditions for the bi-level problem formulations and discuss results that can be extended to obtain multilevel optimization formulations with constraints at each level.
NASA Astrophysics Data System (ADS)
Dharmaseelan, Anoop; Adistambha, Keyne D.
2015-05-01
Fuel cost accounts for 40 percent of the operating cost of an airline. Fuel cost can be minimized by planning a flight on optimized routes. The routes can be optimized by searching best connections based on the cost function defined by the airline. The most common algorithm that used to optimize route search is Dijkstra's. Dijkstra's algorithm produces a static result and the time taken for the search is relatively long. This paper experiments a new algorithm to optimize route search which combines the principle of simulated annealing and genetic algorithm. The experimental results of route search, presented are shown to be computationally fast and accurate compared with timings from generic algorithm. The new algorithm is optimal for random routing feature that is highly sought by many regional operators.
Design optimization of a magnetorheological brake in powered knee orthosis
NASA Astrophysics Data System (ADS)
Ma, Hao; Liao, Wei-Hsin
2015-04-01
Magneto-rheological (MR) fluids have been utilized in devices like orthoses and prostheses to generate controllable braking torque. In this paper, a flat shape rotary MR brake is designed for powered knee orthosis to provide adjustable resistance. Multiple disk structure with interior inner coil is adopted in the MR brake configuration. In order to increase the maximal magnetic flux, a novel internal structure design with smooth transition surface is proposed. Based on this design, a parameterized model of the MR brake is built for geometrical optimization. Multiple factors are considered in the optimization objective: braking torque, weight, and, particularly, average power consumption. The optimization is then performed with Finite Element Analysis (FEA), and the optimal design is obtained among the Pareto-optimal set considering the trade-offs in design objectives.
Assessing transitional phenomena with the transitional object memory probe.
Fowler, C; Hilsenroth, M J; Handler, L
1998-01-01
Winnicott's concept of transitional relatedness has captured the interest of psychoanalysts because it provides an understanding of the dialectical process occurring between inner and outer reality, and by extension, between analyst and analysand. Clinical observations related to transitional phenomena have led the authors to develop a projective early memory probe that assesses transitional phenomena. The transitional object early memory probe was tested both for its empirical validity and for its clinical utility in psychodynamic psychotherapy. Construct validity was assessed by comparing memory scores to the Rorschach Transitional Object Scale, as well as to therapist ratings of patient behaviors. Results demonstrated moderate correlations between early memory scores and Rorschach scale scores. Equally important was the finding that early memory scores were significantly correlated with therapist ratings of key behavioral patterns in therapy. A case vignette highlights the clinical application of the transitional object probe in assessing the capacity for transitional relatedness. In this case, the data gleaned from the patient's memories provided the therapist with a sharper focus on their role in the patient's growing capacity for more vital and creative contact with reality.
Assessing transitional phenomena with the transitional object memory probe.
Fowler, C; Hilsenroth, M J; Handler, L
1998-01-01
Winnicott's concept of transitional relatedness has captured the interest of psychoanalysts because it provides an understanding of the dialectical process occurring between inner and outer reality, and by extension, between analyst and analysand. Clinical observations related to transitional phenomena have led the authors to develop a projective early memory probe that assesses transitional phenomena. The transitional object early memory probe was tested both for its empirical validity and for its clinical utility in psychodynamic psychotherapy. Construct validity was assessed by comparing memory scores to the Rorschach Transitional Object Scale, as well as to therapist ratings of patient behaviors. Results demonstrated moderate correlations between early memory scores and Rorschach scale scores. Equally important was the finding that early memory scores were significantly correlated with therapist ratings of key behavioral patterns in therapy. A case vignette highlights the clinical application of the transitional object probe in assessing the capacity for transitional relatedness. In this case, the data gleaned from the patient's memories provided the therapist with a sharper focus on their role in the patient's growing capacity for more vital and creative contact with reality. PMID:9810109
Intramolecular conformational changes optimize protein kinase C signaling.
Antal, Corina E; Violin, Jonathan D; Kunkel, Maya T; Skovsø, Søs; Newton, Alexandra C
2014-04-24
Optimal tuning of enzyme signaling is critical for cellular homeostasis. We use fluorescence resonance energy transfer reporters in live cells to follow conformational transitions that tune the affinity of a multidomain signal transducer, protein kinase C (PKC), for optimal response to second messengers. This enzyme comprises two diacylglycerol sensors, the C1A and C1B domains, that have a sufficiently high intrinsic affinity for ligand so that the enzyme would be in a ligand-engaged, active state if not for mechanisms that mask its domains. We show that both diacylglycerol sensors are exposed in newly synthesized PKC and that conformational transitions following priming phosphorylations mask the domains so that the lower affinity sensor, the C1B domain, is the primary diacylglycerol binder. The conformational rearrangements of PKC serve as a paradigm for how multimodule transducers optimize their dynamic range of signaling.
Intramolecular conformational changes optimize protein kinase C signaling.
Antal, Corina E; Violin, Jonathan D; Kunkel, Maya T; Skovsø, Søs; Newton, Alexandra C
2014-04-24
Optimal tuning of enzyme signaling is critical for cellular homeostasis. We use fluorescence resonance energy transfer reporters in live cells to follow conformational transitions that tune the affinity of a multidomain signal transducer, protein kinase C (PKC), for optimal response to second messengers. This enzyme comprises two diacylglycerol sensors, the C1A and C1B domains, that have a sufficiently high intrinsic affinity for ligand so that the enzyme would be in a ligand-engaged, active state if not for mechanisms that mask its domains. We show that both diacylglycerol sensors are exposed in newly synthesized PKC and that conformational transitions following priming phosphorylations mask the domains so that the lower affinity sensor, the C1B domain, is the primary diacylglycerol binder. The conformational rearrangements of PKC serve as a paradigm for how multimodule transducers optimize their dynamic range of signaling. PMID:24631122
Reentry trajectory optimization based on a multistage pseudospectral method.
Zhao, Jiang; Zhou, Rui; Jin, Xuelian
2014-01-01
Of the many direct numerical methods, the pseudospectral method serves as an effective tool to solve the reentry trajectory optimization for hypersonic vehicles. However, the traditional pseudospectral method is time-consuming due to large number of discretization points. For the purpose of autonomous and adaptive reentry guidance, the research herein presents a multistage trajectory control strategy based on the pseudospectral method, capable of dealing with the unexpected situations in reentry flight. The strategy typically includes two subproblems: the trajectory estimation and trajectory refining. In each processing stage, the proposed method generates a specified range of trajectory with the transition of the flight state. The full glide trajectory consists of several optimal trajectory sequences. The newly focused geographic constraints in actual flight are discussed thereafter. Numerical examples of free-space flight, target transition flight, and threat avoidance flight are used to show the feasible application of multistage pseudospectral method in reentry trajectory optimization.
Reentry trajectory optimization based on a multistage pseudospectral method.
Zhao, Jiang; Zhou, Rui; Jin, Xuelian
2014-01-01
Of the many direct numerical methods, the pseudospectral method serves as an effective tool to solve the reentry trajectory optimization for hypersonic vehicles. However, the traditional pseudospectral method is time-consuming due to large number of discretization points. For the purpose of autonomous and adaptive reentry guidance, the research herein presents a multistage trajectory control strategy based on the pseudospectral method, capable of dealing with the unexpected situations in reentry flight. The strategy typically includes two subproblems: the trajectory estimation and trajectory refining. In each processing stage, the proposed method generates a specified range of trajectory with the transition of the flight state. The full glide trajectory consists of several optimal trajectory sequences. The newly focused geographic constraints in actual flight are discussed thereafter. Numerical examples of free-space flight, target transition flight, and threat avoidance flight are used to show the feasible application of multistage pseudospectral method in reentry trajectory optimization. PMID:24574929
Reentry Trajectory Optimization Based on a Multistage Pseudospectral Method
Zhou, Rui; Jin, Xuelian
2014-01-01
Of the many direct numerical methods, the pseudospectral method serves as an effective tool to solve the reentry trajectory optimization for hypersonic vehicles. However, the traditional pseudospectral method is time-consuming due to large number of discretization points. For the purpose of autonomous and adaptive reentry guidance, the research herein presents a multistage trajectory control strategy based on the pseudospectral method, capable of dealing with the unexpected situations in reentry flight. The strategy typically includes two subproblems: the trajectory estimation and trajectory refining. In each processing stage, the proposed method generates a specified range of trajectory with the transition of the flight state. The full glide trajectory consists of several optimal trajectory sequences. The newly focused geographic constraints in actual flight are discussed thereafter. Numerical examples of free-space flight, target transition flight, and threat avoidance flight are used to show the feasible application of multistage pseudospectral method in reentry trajectory optimization. PMID:24574929
Management of Klinefelter syndrome during transition.
Gies, Inge; Unuane, David; Velkeniers, Brigitte; De Schepper, Jean
2014-08-01
Klinefelter syndrome (KS) is the most common sex chromosomal disorder in males. Key findings in older adolescents and young men are small testes with variable hypo-androgenism, but almost universal azoospermia, most frequently in combination with a history of learning difficulties and behavior problems. Males with KS may come to medical attention through different medical presentations, given its association with several congenital malformations, and psychiatric, endocrine, and metabolic disorders. Preventive care is to be provided from diagnosis, preferentially through a multidisciplinary approach, including that from an endocrinologist, clinical psychologist or psychiatrist, neurologist, urologist, geneticist, sexologist, and a fertility team. Accurate information about the condition and assessment of associated medical conditions should be offered at diagnosis and should be followed by psychological counseling. Medical treatment during transition into adulthood is focused on fertility preservation and testosterone replacement therapy in the case of hypo-androgenism, and alleviation of current or future consequences of testicular fibrosis. However, more research is needed to determine the need for pro-active testosterone treatment in adolescence, as well as the conditions for an optimal testosterone replacement and sperm retrieval in adolescents and young men with KS. Furthermore, screening for associated diseases such as metabolic syndrome, autoimmune diseases, thyroid dysfunction, and malignancies is warranted during this period of life. The practical medical management during transition and, more specifically, the role of the endocrinologist are discussed in this article. PMID:24801585
The KELT Survey for Transiting Planets
NASA Astrophysics Data System (ADS)
Oberst, T. E.; Beatty, T. G.; Bieryla, A.; Bozza, V.; Collins, K.; D'Ago, G.; Eastman, J. D.; Gaudi, B. S.; Jang-Condell, H.; Jensen, E. L. N.; Kielkopf, J.; Lund, M. B.; Manner, M.; McLeod, K. K.; Novati, S. C.; Penny, M. T.; Pepper, J.; Reed, P. A.; Rodriguez, J. E.; Scarpetta, G.; Siverd, R. J.; Stassun, K. G.; Street, R. A.
2014-03-01
KELT (the Kilodegree Extremely Little Telescope) is a transit survey for new exoplanets orbiting bright (8 < V < 10) stars. Such systems are ideally suited for high signal-to-noise follow-up studies of planetary atmospheres and compositions by current ground- and spaced-based observatories. KELT consists of two small-aperture, wide-field, robotic telescopes which have been monitoring ~ 50 % of the northern and southern skies for 6 and 3.5 years, respectively. Identification and vetting of candidates is ongoing. The survey has thus far discovered and confirmed three transiting planets - hot Jupiters KELT-2Ab and KELT-3b, and hot Saturn KELT- 6b - as well as the 27 MJ brown dwarf KELT-1b. The KELT Follow-up Network, a collaboration of over 20 amateur and professional astronomers and institutions, is actively confirming additional KELT discoveries. The Network has also started observing other interesting targets. While KELT is optimized for detecting gas giant companions of FGK stars, the Network is helping to observe Kepler-discovered eclipsing binaries and circumbinary planetary systems, potential super-Earths orbiting M dwarfs, and other variable stars and eclipsing binaries.
Optimal TCSC placement for optimal power flow
NASA Astrophysics Data System (ADS)
Lakdja, Fatiha; Zohra Gherbi, Fatima; Berber, Redouane; Boudjella, Houari
2012-11-01
Very few publications have been focused on the mathematical modeling of Flexible Alternating Current Transmission Systems (FACTS) -devices in optimal power flow analysis. A Thyristor Controlled Series Capacitors (TCSC) model has been proposed, and the model has been implemented in a successive QP. The mathematical models for TCSC have been established, and the Optimal Power Flow (OPF) problem with these FACTS-devices is solved by Newtons method. This article employs the Newton- based OPF-TCSC solver of MATLAB Simulator, thus it is essential to understand the development of OPF and the suitability of Newton-based algorithms for solving OPF-TCSC problem. The proposed concept was tested and validated with TCSC in twenty six-bus test system. Result shows that, when TCSC is used to relieve congestion in the system and the investment on TCSC can be recovered, with a new and original idea of integration.
Optimal reconstruction of images from localized phase.
Urieli, S; Porat, M; Cohen, N
1998-01-01
The importance of localized phase in signal representation is investigated. The convergence rate of the POCS algorithm (projection onto convex sets) used for image reconstruction from spectral phase is defined and analyzed, and the characteristics of images optimally reconstructed from phase-only information are presented. It is concluded that images of geometric form are most efficiently reconstructed from their spectral phase, whereas images of symmetric form have the poorest convergence characteristics. The transition between the two extremes is shown to be continuous. The results provide a new approach and analysis of the previously reported advantages of the localized phase representation over the global approach, and suggest possible compression schemes.
Selenophene transition metal complexes
White, C.J.
1994-07-27
This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the {eta}{sup 5}- and the {eta}{sup 1}(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The {sup 77}Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of {eta}{sup 1}(S)-bound thiophenes, {eta}{sup 1}(S)-benzothiophene and {eta}{sup 1}(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the {eta}{sup 1}(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh{sub 3})Re(2-benzothioenylcarbene)]O{sub 3}SCF{sub 3} was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the {eta}{sup 1}(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.
22 CFR 41.71 - Transit aliens.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...
22 CFR 41.71 - Transit aliens.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...
22 CFR 41.71 - Transit aliens.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...
22 CFR 41.71 - Transit aliens.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...
22 CFR 41.71 - Transit aliens.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...
Stochastic Optimal Control via Bellman's Principle
NASA Technical Reports Server (NTRS)
Crespo, Luis G.; Sun, Jian Q.
2003-01-01
This paper presents a method for finding optimal controls of nonlinear systems subject to random excitations. The method is capable to generate global control solutions when state and control constraints are present. The solution is global in the sense that controls for all initial conditions in a region of the state space are obtained. The approach is based on Bellman's Principle of optimality, the Gaussian closure and the Short-time Gaussian approximation. Examples include a system with a state-dependent diffusion term, a system in which the infinite hierarchy of moment equations cannot be analytically closed, and an impact system with a elastic boundary. The uncontrolled and controlled dynamics are studied by creating a Markov chain with a control dependent transition probability matrix via the Generalized Cell Mapping method. In this fashion, both the transient and stationary controlled responses are evaluated. The results show excellent control performances.
Jamming transition in hierarchical networks
NASA Astrophysics Data System (ADS)
Cheng, Xiang; Boettcher, Stefan
2014-03-01
Jamming transitions arise in disordered granular materials where the systems fall out of equilibrium due to an increase in the packing density. A kinetically constrained lattice gas model due to Biroli and Mezard (BM) has connected the jamming transition to an equilibrium phase transition. In this description, before this equilibrium transition can be reached, any experiment or simulation would fall out of equilibrium at a Kauzmann transition. However, this analysis is based on a mean-field calculation which, for disordered systems, may have limited relevance in finite dimensions. We study the BM-model on a lattice-like network, which mixes geometric and mean-field features, to reproduce such a phase transition. Computationally, we use the Wang-Landau algorithm which should be less affected by the jamming near the phase transition. The algorithm produces the density of states and, hence, the entropy directly, in addition to many critical properties, such as packing fraction, compressibility, etc. Also, lattice-like hierarchical networks conveniently allow exact or approximate renormalization group treatments, extending analytical results to the thermodynamic limit. Supported through NSF grant DMR-1207431.
The Visibility of Earth Transits
NASA Technical Reports Server (NTRS)
Castellano, Timothy P.; Doyle, Laurance; McIntosh, Dawn; DeVincenzi, Donald (Technical Monitor)
2000-01-01
The recent photometric detection of planetary transits of the solar-like star HD 209458 at a distance of 47 parsecs suggest that transits can reveal the presence of Jupiter-size planetary companions in the solar neighborhood. Recent space-based transit searches have achieved photometric precision within an order of magnitude of that required to detect the much smaller transit signal of an earth-size planet across a solar-size star. Laboratory experiments in the presence of realistic noise sources have shown that CCDs can achieve photometric precision adequate to detect the 9.6 E-5 dimming of the Sun due to a transit of the Earth. Space-based solar irradiance monitoring has shown that the intrinsic variability of the Sun would not preclude such a detection. Transits of the Sun by the Earth would be detectable by observers that reside within a narrow band of sky positions near the ecliptic plane, if the observers possess current Earth epoch levels of technology and astronomical expertise. A catalog of solar-like stars that satisfy the geometric condition for Earth transit visibility are presented.
The Visibility of Earth Transits
NASA Technical Reports Server (NTRS)
Castellano, Tim; DeVincenzi, Donald L. (Technical Monitor)
2000-01-01
The recent detection of planetary transits of the solar-like star HD 209458 at a distance of 47 parsecs suggest that transits can reveal the presence of Jupiter-size planetary companions in the solar neighborhood. Recent space-based transit searches have achieved photometric precision within an order of magnitude of that required to detect the much smaller transit signal of an earth-size planet around a solar-size star. Laboratory experiments in the presence of realistic noise sources have shown that CCDs can achieve photometric precision adequate to detect the 9.6 E-5 dimming, of the Sun due to a transit of the Earth. Space-based solar irradiance monitoring has shown that the intrinsic variability of the Sun would not preclude such a detection. Transits of the Sun by the Earth would be detectable by observers that reside within a narrow band of sky positions near the ecliptic plane, if the observers possess current Earth epoch levels of technology and astronomical expertise. A catalog of candidate target stars, their properties, and simulations of the photometric Earth transit signal detectability at each target is presented.
Observational biases for transiting planets
NASA Astrophysics Data System (ADS)
Kipping, David M.; Sandford, Emily
2016-09-01
Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 AU of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.
Electronic Transitions of Yttrium Monophosphide
NASA Astrophysics Data System (ADS)
Cheung, Allan S. C.; Li, Biu Wa; Chan, MAN-CHOR
2015-06-01
Electronic transition spectrum of the yttrium monophosphide (YP) molecule in the visible region between 715 nm and 880 nm has been recorded using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The YP molecule was produced by reacting laser - ablated yttrium atoms with PH3 seeded in argon. Thirteen vibrational bands were analyzed and five electronic transition systems have identified, namely the [12.2] Ω = 3 - X3 Π_2 transition, [13.3] Ω = 3 - X3 Π_2 transition, [13.4] Ω = 3 - X3 Π_2 transition, [13.5] Ω = 3 - X3 Π_2 transition, and [13.4] Ω = 2 - X3 Π_2 transition. Least squares fits of the measured rotational lines yielded molecular constants for the ground and excited states. The ground state symmetry and the bond length r_0 of the YP molecule have been determined to be a X3 Π_2 state and 2.4413 Å respectively in this work. A molecular orbital energy level diagram has been used to help the assignment of the observed electronic states. This work represents the first experimental investigation of the spectrum of the YP molecule.
Major evolutionary transitions in individuality
West, Stuart A.; Fisher, Roberta M.; Gardner, Andy; Kiers, E. Toby
2015-01-01
The evolution of life on earth has been driven by a small number of major evolutionary transitions. These transitions have been characterized by individuals that could previously replicate independently, cooperating to form a new, more complex life form. For example, archaea and eubacteria formed eukaryotic cells, and cells formed multicellular organisms. However, not all cooperative groups are en route to major transitions. How can we explain why major evolutionary transitions have or haven’t taken place on different branches of the tree of life? We break down major transitions into two steps: the formation of a cooperative group and the transformation of that group into an integrated entity. We show how these steps require cooperation, division of labor, communication, mutual dependence, and negligible within-group conflict. We find that certain ecological conditions and the ways in which groups form have played recurrent roles in driving multiple transitions. In contrast, we find that other factors have played relatively minor roles at many key points, such as within-group kin discrimination and mechanisms to actively repress competition. More generally, by identifying the small number of factors that have driven major transitions, we provide a simpler and more unified description of how life on earth has evolved. PMID:25964342
Optimal control computer programs
NASA Technical Reports Server (NTRS)
Kuo, F.
1992-01-01
The solution of the optimal control problem, even with low order dynamical systems, can usually strain the analytical ability of most engineers. The understanding of this subject matter, therefore, would be greatly enhanced if a software package existed that could simulate simple generic problems. Surprisingly, despite a great abundance of commercially available control software, few, if any, address the part of optimal control in its most generic form. The purpose of this paper is, therefore, to present a simple computer program that will perform simulations of optimal control problems that arise from the first necessary condition and the Pontryagin's maximum principle.
Thermophotovoltaic Array Optimization
SBurger; E Brown; K Rahner; L Danielson; J Openlander; J Vell; D Siganporia
2004-07-29
A systematic approach to thermophotovoltaic (TPV) array design and fabrication was used to optimize the performance of a 192-cell TPV array. The systematic approach began with cell selection criteria that ranked cells and then matched cell characteristics to maximize power output. Following cell selection, optimization continued with an array packaging design and fabrication techniques that introduced negligible electrical interconnect resistance and minimal parasitic losses while maintaining original cell electrical performance. This paper describes the cell selection and packaging aspects of array optimization as applied to fabrication of a 192-cell array.
2014-05-13
ROL provides interfaces to and implementations of algorithms for gradient-based unconstrained and constrained optimization. ROL can be used to optimize the response of any client simulation code that evaluates scalar-valued response functions. If the client code can provide gradient information for the response function, ROL will take advantage of it, resulting in faster runtimes. ROL's interfaces are matrix-free, in other words ROL only uses evaluations of scalar-valued and vector-valued functions. ROL can be used tomore » solve optimal design problems and inverse problems based on a variety of simulation software.« less
Contingency contractor optimization.
Gearhart, Jared Lee; Adair, Kristin Lynn; Jones, Katherine A.; Bandlow, Alisa; Durfee, Justin David.; Jones, Dean A.; Martin, Nathaniel; Detry, Richard Joseph; Nanco, Alan Stewart; Nozick, Linda Karen
2013-10-01
The goal of Phase 3 the OSD ATL Contingency Contractor Optimization (CCO) project is to create an engineering prototype of a tool for the contingency contractor element of total force planning during the Support for Strategic Analysis (SSA). An optimization model was developed to determine the optimal mix of military, Department of Defense (DoD) civilians, and contractors that accomplishes a set of user defined mission requirements at the lowest possible cost while honoring resource limitations and manpower use rules. An additional feature allows the model to understand the variability of the Total Force Mix when there is uncertainty in mission requirements.
Contingency contractor optimization.
Gearhart, Jared Lee; Adair, Kristin Lynn; Jones, Katherine A.; Bandlow, Alisa; Detry, Richard Joseph; Durfee, Justin David.; Jones, Dean A.; Martin, Nathaniel; Nanco, Alan Stewart; Nozick, Linda Karen
2013-06-01
The goal of Phase 3 the OSD ATL Contingency Contractor Optimization (CCO) project is to create an engineering prototype of a tool for the contingency contractor element of total force planning during the Support for Strategic Analysis (SSA). An optimization model was developed to determine the optimal mix of military, Department of Defense (DoD) civilians, and contractors that accomplishes a set of user defined mission requirements at the lowest possible cost while honoring resource limitations and manpower use rules. An additional feature allows the model to understand the variability of the Total Force Mix when there is uncertainty in mission requirements.
NASA Astrophysics Data System (ADS)
Furniss, S. G.
1989-10-01
While an SSTO with airbreathing propulsion for initial acceleration may greatly reduce future payload launch costs, such vehicles exhibit extreme sensitivity to design assumptions; the process of vehicle optimization is, accordingly, a difficult one. Attention is presently given to the role in optimization of the design mission, fuselage geometry, and the means employed to furnish adequate pitch and directional control. The requirements influencing wing design and scaling are also discussed. The Saenger and Hotol designs are the illustrative cases noted in this generalizing consideration of the SSTO-optimization process.
High-efficiency transition between rectangular waveguide and domino plasmonic waveguide
NASA Astrophysics Data System (ADS)
Liu, Liangliang; Li, Zhuo; Xu, Bingzheng; Gu, Changqing; Chen, Chen; Ning, Pingping; Yan, Jian; Chen, Xingyu
2015-02-01
In this work, we propose an optimized transition structure to realize smooth and high efficiency conversion from the guided wave supported by a conventional rectangular waveguide (CRW) to the domino plasmon polaritons (DPPs) supported by a domino plasmonic waveguide (DPW) and vice versa in the X-band (8.2GHz˜12.4GHz). This transition structure consists of two tapered CRWs connected by a gradient domino array with optimized gradient heights and lateral widths. Experimental results of the S-parameters show excellent agreement with the simulations and the optimization scheme can be readily extended to other bands. Furthermore, a domino plasmonic power divider is implemented to demonstrate the application of the transition structure in the integration of conventional microwave circuits with plasmonic devices.
Fluctuation driven electroweak phase transition
NASA Technical Reports Server (NTRS)
Gleiser, Marcelo; Kolb, Edward W.
1991-01-01
We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.
Nonradiative transition dynamics in alexandrite
NASA Technical Reports Server (NTRS)
Gayen, S. K.; Wang, W. B.; Petricevic, V.; Alfano, R. R.
1986-01-01
The first direct picosecond time-resolved measurement of the nonradiative transition dynamics between the excited 4T2 pump band and the metastable 2E storage level of the trivalent chromium ion in alexandrite is reported. The nonradiative relaxation times of 17 ps for intra-4T2 vibrational transitions, and 27 ps for 4T2-2E electronic transition are obtained. The thermal repopulation rate of the 4T2 state from the metastable 2E level is of the order 3.5 x 10 to the 9th per s.
Evolution of weighted complex bus transit networks with flow
NASA Astrophysics Data System (ADS)
Huang, Ailing; Xiong, Jie; Shen, Jinsheng; Guan, Wei
2016-02-01
Study on the intrinsic properties and evolutional mechanism of urban public transit networks (PTNs) has great significance for transit planning and control, particularly considering passengers’ dynamic behaviors. This paper presents an empirical analysis for exploring the complex properties of Beijing’s weighted bus transit network (BTN) based on passenger flow in L-space, and proposes a bi-level evolution model to simulate the development of transit routes from the view of complex network. The model is an iterative process that is driven by passengers’ travel demands and dual-controlled interest mechanism, which is composed of passengers’ spatio-temporal requirements and cost constraint of transit agencies. Also, the flow’s dynamic behaviors, including the evolutions of travel demand, sectional flow attracted by a new link and flow perturbation triggered in nearby routes, are taken into consideration in the evolutional process. We present the numerical experiment to validate the model, where the main parameters are estimated by using distribution functions that are deduced from real-world data. The results obtained have proven that our model can generate a BTN with complex properties, such as the scale-free behavior or small-world phenomenon, which shows an agreement with our empirical results. Our study’s results can be exploited to optimize the real BTN’s structure and improve the network’s robustness.
Presence of state transitions in the cryptophyte alga Guillardia theta
Cheregi, Otilia; Kotabová, Eva; Prášil, Ondřej; Schröder, Wolfgang P.; Kaňa, Radek; Funk, Christiane
2015-01-01
Plants and algae have developed various regulatory mechanisms for optimal delivery of excitation energy to the photosystems even during fluctuating light conditions; these include state transitions as well as non-photochemical quenching. The former process maintains the balance by redistributing antennae excitation between the photosystems, meanwhile the latter by dissipating excessive excitation inside the antennae. In the present study, these mechanisms have been analysed in the cryptophyte alga Guillardia theta. Photoprotective non-photochemical quenching was observed in cultures only after they had entered the stationary growth phase. These cells displayed a diminished overall photosynthetic efficiency, measured as CO2 assimilation rate and electron transport rate. However, in the logarithmic growth phase G. theta cells redistributed excitation energy via a mechanism similar to state transitions. These state transitions were triggered by blue light absorbed by the membrane integrated chlorophyll a/c antennae, and green light absorbed by the lumenal biliproteins was ineffective. It is proposed that state transitions in G. theta are induced by small re-arrangements of the intrinsic antennae proteins, resulting in their coupling/uncoupling to the photosystems in state 1 or state 2, respectively. G. theta therefore represents a chromalveolate algae able to perform state transitions. PMID:26254328
Unsteady transitions of separation patterns in single expansion ramp nozzle
NASA Astrophysics Data System (ADS)
Yu, Y.; Xu, J.; Yu, K.; Mo, J.
2015-11-01
The single expansion ramp nozzle is one of the optimal configurations for a planar rocket-based combined cycle engine because of its good integration and self-adaptability at off-design operation. The single expansion ramp nozzle is seriously overexpanded when the vehicle is at low speed, resulting in complex flow separation phenomena. Several separation patterns have been found in the single expansion ramp nozzle. Numerical simulations have shown that the transition between these separation patterns occurs in the nozzle startup and shutdown processes. However, only a few relevant experimental studies have been reported. This study reproduces the nozzle startup and shutdown processes using wind tunnel experiments. Two restricted shock separation patterns are observed in the experiment, namely, a separation bubble either forms on the ramp or the flap. The detailed flow fields in the transition processes are captured using a high-speed camera. The shock wave structures in the two separation patterns, influences of the nozzle pressure ratio (NPR) on the separation patterns and changes of the shock waves in the transition processes are discussed in detail. Shock wave instabilities accompany the separation transition, which usually takes less than 5 ms. The nozzle pressure ratios corresponding to the separation pattern transition are different in the startup and shutdown processes, which leads to a hysteresis effect.
[Transition to adulthood of adolescents with inflammatory bowel disease].
Navarro, Elizabeth; Ossa, Juan C; Simian, Daniela; Quera, Rodrigo
2015-06-01
Inflammatory bowel disease (IBD) is a prevalent chronic disorder, often diagnosed during childhood. Studies have suggested that the incidence of IBD in this group of patients is increasing. Children and adolescents with IBD frequently have more extensive and severe disease than adults. Transition is an important concept to ensure optimal health care management of adolescents and young adult patients with chronic physical and medical conditions. During this process there is a change in knowledge, attitudes and behavior towards the disease with a responsibility that gradually shifts from parents to the patient. The success of the transition process depends on the patient, pediatric and adult gastroenterologists. Thus, providers need to understand how to start, maintain and finish this process. When transition process is coordinated, staged and well planned, the adolescent and young adult will acquire the tools needed to successfully self-manage his or her own medical condition. Rather than a universal model of transition, each institution needs to adapt the most efficient model. The aim of this article is to review concepts pertinent to transition management for adolescents and young adults with IBD. PMID:26230560
Recent progress in the development of transition radiation detectors
NASA Technical Reports Server (NTRS)
Cherry, M. L.; Hartmann, G.; Prince, T.; Mueller, D.
1978-01-01
Transition-radiation detectors have been used in several recent cosmic-ray experiments for particle identification at energies E/mc-squared of at least about 1000. In order to optimize the design of such detectors and to use them for energy measurements over a broad energy range, it is necessary to study the details of the transition-radiation process. Experimental results are presented which test the theoretical predictions more precisely and at higher energies than in previous experiments. The dependence of the interference pattern in the frequency spectrum on the radiator dimensions is studied, and the total transition-radiation yield generated by electrons in various radiators is measured over a very wide energy range, from 5 to 300 GeV. The significance of the individual experimental parameters in the design of transition radiation detectors is reviewed, and the characteristics of transition-radiation detectors capable of measuring particle energies over the range E/mc-squared from about 300 to 100,000 are discussed.
Empowering Students in Transition
Sullivan, Ann-Catherine
2016-01-01
The purpose of this study was to (a) identify potential benefits for students with disabilities taking part in a physical activity program with same-age typical peers on a Midwest university campus and (b) to determine if the program impacted the students with disabilities empowerment. Empowerment theory was used to determine how transition students’ attitudes change over the course of the semester while participating in a workout buddy program with same-age college peers. The program was structured to provide a sense of empowerment to students to make their own decisions and learn for themselves so they do not feel a lack of power in their lives. This study implemented elements of a quantitative design but a majority utilized a qualitative design based on the assumptions of the Interpretivist paradigm. The quantitative design elements focused on the analysis of two questionnaires: Sports Questionnaire and the Perceived Control Scale Questionnaire. The analysis of the focus group data revealed the following themes as positive effects of the intervention: positive effect on empowerment, how happy the program made the students, what benefits the students gained from the program, the student’s familiarity with university students, and the environment, and, lastly, the students ability to ask for assistance when need. Findings from the study determined that the empowerment of the students with disabilities was impacted while participating in the program. In general, the findings of gaining empowerment were similar to previous studies in that students with disabilities are able to gain empowerment from participation in fitness and recreation programs. The researcher noted during focus groups that some of the Best of Both Worlds (BOBW) students were not confident in starting conversations with their university peers. Although the BOBW students felt a sense of losing empowerment with this specific instance, there was an overall positive impact on the BOBW students
Immigration and adult transitions.
Rumbaut, Rubén G; Komaie, Golnaz
2010-01-01
Almost 30 percent of the more than 68 million young adults aged eighteen to thirty-four in the United States today are either foreign born or of foreign parentage. As these newcomers make their transitions to adulthood, say Rubén Rumbaut and Golnaz Komaie, they differ significantly not only from one another but also from their native-parentage counterparts, including blacks and whites. The authors document the demographic changes in the United States over the past forty years and describe the ways in which generation and national origin shape the experiences of these newcomers as they become adults. Rumbaut and Komaie point out that immigrant groups experience gaps in social, economic, and legal status that are even greater than the gaps between native whites and blacks. By far the most-educated (Indians) and the least-educated (Mexicans) groups in the United States today are first-generation immigrants, as are the groups with the lowest poverty rate (Filipinos) and the highest poverty rate (Dominicans). These social and economic divides reflect three very different ways immigrants enter the country: through regular immigration channels, without legal authorization, or as state-sponsored refugees. For many ethnic groups, significant progress takes place from the first to the second generation. But, say the authors, for millions of young immigrants, a lack of legal permanent residency status blocks their prospects for social mobility. Having an undocumented status has become all the more consequential with the failure of Congress to pass comprehensive federal immigration reforms. In the coming two decades, as the U.S. native-parentage labor force continues to shrink, immigrants and their children are expected to account for most of the growth of the nation's labor force, with the fastest-growing occupations requiring college degrees. Rumbaut and Komaie stress that one key to the nation's future will be how it incorporates young adults of immigrant origin in its
Library for Nonlinear Optimization
2001-10-09
OPT++ is a C++ object-oriented library for nonlinear optimization. This incorporates an improved implementation of an existing capability and two new algorithmic capabilities based on existing journal articles and freely available software.
Alicia Hofler; Pavel Evtushenko
2007-07-03
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. A genetic algorithm (GA) has been successfully used to optimize DC photo injector designs at Cornell University [1] and Jefferson Lab [2]. We propose to apply GA techniques to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize a system that has been benchmarked with beam measurements and simulation.
General shape optimization capability
NASA Technical Reports Server (NTRS)
Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson
1991-01-01
A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.
A. S. Hofler; P. Evtushenko; M. Krasilnikov
2007-08-01
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. RF and SRF gun design is further complicated because the bunches are space charge dominated and require additional emittance compensation. A genetic algorithm has been successfully used to optimize DC photo injector designs for Cornell* and Jefferson Lab**, and we propose studying how the genetic algorithm techniques can be applied to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize gun designs that have been benchmarked with beam measurements and simulation.
Topology optimized microbioreactors.
Schäpper, Daniel; Lencastre Fernandes, Rita; Lantz, Anna Eliasson; Okkels, Fridolin; Bruus, Henrik; Gernaey, Krist V
2011-04-01
This article presents the fusion of two hitherto unrelated fields--microbioreactors and topology optimization. The basis for this study is a rectangular microbioreactor with homogeneously distributed immobilized brewers yeast cells (Saccharomyces cerevisiae) that produce a recombinant protein. Topology optimization is then used to change the spatial distribution of cells in the reactor in order to optimize for maximal product flow out of the reactor. This distribution accounts for potentially negative effects of, for example, by-product inhibition. We show that the theoretical improvement in productivity is at least fivefold compared with the homogeneous reactor. The improvements obtained by applying topology optimization are largest where either nutrition is scarce or inhibition effects are pronounced.
TOOLKIT FOR ADVANCED OPTIMIZATION
2000-10-13
The TAO project focuses on the development of software for large scale optimization problems. TAO uses an object-oriented design to create a flexible toolkit with strong emphasis on the reuse of external tools where appropriate. Our design enables bi-directional connection to lower level linear algebra support (for example, parallel sparse matrix data structures) as well as higher level application frameworks. The Toolkist for Advanced Optimization (TAO) is aimed at teh solution of large-scale optimization problemsmore » on high-performance architectures. Our main goals are portability, performance, scalable parallelism, and an interface independent of the architecture. TAO is suitable for both single-processor and massively-parallel architectures. The current version of TAO has algorithms for unconstrained and bound-constrained optimization.« less
Singh, Sanjay; Caron, Luana; D'Souza, Sunil Wilfred; Fichtner, Tina; Porcari, Giacomo; Fabbrici, Simone; Shekhar, Chandra; Chadov, Stanislav; Solzi, Massimo; Felser, Claudia
2016-05-01
In contrast to rare-earth-based materials, cheaper and more environmentally friendly candidates for cooling applications are found within the family of Ni-Mn Heusler alloys. Initial interest in these materials is focused on the first-order magnetostructural transitions. However, large hysteresis makes a magnetocaloric cycle irreversible. Alternatively, here it is shown how the Heusler family can be used to optimize reversible second-order magnetic phase transitions for magnetocaloric applications. PMID:26928954
Singh, Sanjay; Caron, Luana; D'Souza, Sunil Wilfred; Fichtner, Tina; Porcari, Giacomo; Fabbrici, Simone; Shekhar, Chandra; Chadov, Stanislav; Solzi, Massimo; Felser, Claudia
2016-05-01
In contrast to rare-earth-based materials, cheaper and more environmentally friendly candidates for cooling applications are found within the family of Ni-Mn Heusler alloys. Initial interest in these materials is focused on the first-order magnetostructural transitions. However, large hysteresis makes a magnetocaloric cycle irreversible. Alternatively, here it is shown how the Heusler family can be used to optimize reversible second-order magnetic phase transitions for magnetocaloric applications.
Modeling using optimization routines
NASA Technical Reports Server (NTRS)
Thomas, Theodore
1995-01-01
Modeling using mathematical optimization dynamics is a design tool used in magnetic suspension system development. MATLAB (software) is used to calculate minimum cost and other desired constraints. The parameters to be measured are programmed into mathematical equations. MATLAB will calculate answers for each set of inputs; inputs cover the boundary limits of the design. A Magnetic Suspension System using Electromagnets Mounted in a Plannar Array is a design system that makes use of optimization modeling.
Kawase, Mitsuhiro
2009-11-22
The zipped file contains a directory of data and routines used in the NNMREC turbine depth optimization study (Kawase et al., 2011), and calculation results thereof. For further info, please contact Mitsuhiro Kawase at kawase@uw.edu. Reference: Mitsuhiro Kawase, Patricia Beba, and Brian Fabien (2011), Finding an Optimal Placement Depth for a Tidal In-Stream Conversion Device in an Energetic, Baroclinic Tidal Channel, NNMREC Technical Report.
ISS Update commentator Brandi Dean interviews Mario Runco, NASA astronaut, about Venus's transit across the sun on June 5, 2012. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #...
Adolescent Urology and Transitional Care.
Woodhouse, Christopher
2015-11-01
Babies with the major congenital anomalies of the genito-urinary tract have all-embracing holistic care during childhood. They require the same level of care in adult life. This is the role of transition and adolescent urology.
NASA Astrophysics Data System (ADS)
Bueter, C.
2013-04-01
Enticing by virtue of its predictability, historical utility, and spectacle, the transit of Venus is a niche event among astronomical phenomena. Though the value of a transit for scientific purposes is now diminished, the brief appearance of Venus silhouetted against the background of the Sun in 2004 moved the artistic community to celebrate the rare alignment. Artists of all ages combined old traditions with fresh technology to create a 21st-century tapestry of music, sculpture, paintings, glasswork, quilts, sky shows, and digital imagery. A full catalog of transit-related art generated over the centuries would feature the sampling of entries presented here and at the Moved by a Rapid Transit website.
NASA Astrophysics Data System (ADS)
Wecker, Dave; Hastings, Matthew B.; Troyer, Matthias
2016-08-01
We study a variant of the quantum approximate optimization algorithm [E. Farhi, J. Goldstone, and S. Gutmann, arXiv:1411.4028] with a slightly different parametrization and a different objective: rather than looking for a state which approximately solves an optimization problem, our goal is to find a quantum algorithm that, given an instance of the maximum 2-satisfiability problem (MAX-2-SAT), will produce a state with high overlap with the optimal state. Using a machine learning approach, we chose a "training set" of instances and optimized the parameters to produce a large overlap for the training set. We then tested these optimized parameters on a larger instance set. As a training set, we used a subset of the hard instances studied by Crosson, Farhi, C. Y.-Y. Lin, H.-H. Lin, and P. Shor (CFLLS) (arXiv:1401.7320). When tested, on the full set, the parameters that we find produce a significantly larger overlap than the optimized annealing times of CFLLS. Testing on other random instances from 20 to 28 bits continues to show improvement over annealing, with the improvement being most notable on the hardest instances. Further tests on instances of MAX-3-SAT also showed improvement on the hardest instances. This algorithm may be a possible application for near-term quantum computers with limited coherence times.
Thermoacoustic Refrigerator's Stack Optimization
NASA Astrophysics Data System (ADS)
El-Fawal, Mawahib Hassan; Mohd-Ghazali, Normah; Yaacob, Mohd. Shafik; Darus, Amer Nordin
2010-06-01
The standing wave thermoacoustic refrigerator, which uses sound generation to transfer heat, was developed rapidly during the past four decades. It was regarded as a new, promising and environmentally benign alternative to conventional compression vapor refrigerators, although it was not competitive regarding the coefficient of performance (COP) yet. Thus the aim of this paper is to enhance thermoacoustic refrigerator's stack performance through optimization. A computational optimization procedure of thermoacoustic stack design was fully developed. The procedure was designed to achieve optimal coefficient of performance based on most of the design and operating parameters. Cooling load and acoustic power governing equations were set assuming the linear thermoacoustic theory. Lagrange multipliers method was used as an optimization technique tool to solve the governing equations. Numerical analyses results of the developed design procedure are presented. The results showed that the stack design parameters are the most significant parameters for the optimal overall performance. The coefficient of performance obtained increases by about 48.8% from the published experimental optimization methods. The results are in good agreement with past established studies.
Cyclone performance and optimization
Leith, D.
1990-09-15
The objectives of this project are: to characterize the gas flow pattern within cyclones, to revise the theory for cyclone performance on the basis of these findings, and to design and test cyclones whose dimensions have been optimized using revised performance theory. This work is important because its successful completion will aid in the technology for combustion of coal in pressurized, fluidized beds. This quarter, an empirical model for predicting pressure drop across a cyclone was developed through a statistical analysis of pressure drop data for 98 cyclone designs. The model is shown to perform better than the pressure drop models of First (1950), Alexander (1949), Barth (1956), Stairmand (1949), and Shepherd-Lapple (1940). This model is used with the efficiency model of Iozia and Leith (1990) to develop an optimization curve which predicts the minimum pressure drop and the dimension rations of the optimized cyclone for a given aerodynamic cut diameter, d{sub 50}. The effect of variation in cyclone height, cyclone diameter, and flow on the optimization curve is determined. The optimization results are used to develop a design procedure for optimized cyclones. 37 refs., 10 figs., 4 tabs.
Regularizing portfolio optimization
NASA Astrophysics Data System (ADS)
Still, Susanne; Kondor, Imre
2010-07-01
The optimization of large portfolios displays an inherent instability due to estimation error. This poses a fundamental problem, because solutions that are not stable under sample fluctuations may look optimal for a given sample, but are, in effect, very far from optimal with respect to the average risk. In this paper, we approach the problem from the point of view of statistical learning theory. The occurrence of the instability is intimately related to over-fitting, which can be avoided using known regularization methods. We show how regularized portfolio optimization with the expected shortfall as a risk measure is related to support vector regression. The budget constraint dictates a modification. We present the resulting optimization problem and discuss the solution. The L2 norm of the weight vector is used as a regularizer, which corresponds to a diversification 'pressure'. This means that diversification, besides counteracting downward fluctuations in some assets by upward fluctuations in others, is also crucial because it improves the stability of the solution. The approach we provide here allows for the simultaneous treatment of optimization and diversification in one framework that enables the investor to trade off between the two, depending on the size of the available dataset.
Universal Keplerian state transition matrix
NASA Technical Reports Server (NTRS)
Shepperd, S. W.
1985-01-01
A completely general method for computing the Keplerian state transition matrix in terms of Goodyear's universal variables is presented. This includes a new scheme for solving Kepler's problem which is a necessary first step to computing the transition matrix. The Kepler problem is solved in terms of a new independent variable requiring the evaluation of only one transcendental function. Furthermore, this transcendental function may be conveniently evaluated by means of a Gaussian continued fraction.
When teams shift among processes: insights from simulation and optimization.
Kennedy, Deanna M; McComb, Sara A
2014-09-01
This article introduces process shifts to study the temporal interplay among transition and action processes espoused in the recurring phase model proposed by Marks, Mathieu, and Zacarro (2001). Process shifts are those points in time when teams complete a focal process and change to another process. By using team communication patterns to measure process shifts, this research explores (a) when teams shift among different transition processes and initiate action processes and (b) the potential of different interventions, such as communication directives, to manipulate process shift timing and order and, ultimately, team performance. Virtual experiments are employed to compare data from observed laboratory teams not receiving interventions, simulated teams receiving interventions, and optimal simulated teams generated using genetic algorithm procedures. Our results offer insights about the potential for different interventions to affect team performance. Moreover, certain interventions may promote discussions about key issues (e.g., tactical strategies) and facilitate shifting among transition processes in a manner that emulates optimal simulated teams' communication patterns. Thus, we contribute to theory regarding team processes in 2 important ways. First, we present process shifts as a way to explore the timing of when teams shift from transition to action processes. Second, we use virtual experimentation to identify those interventions with the greatest potential to affect performance by changing when teams shift among processes. Additionally, we employ computational methods including neural networks, simulation, and optimization, thereby demonstrating their applicability in conducting team research.
Klammer, Martin; Dybowski, J. Nikolaj; Hoffmann, Daniel; Schaab, Christoph
2015-01-01
Multivariate biomarkers that can predict the effectiveness of targeted therapy in individual patients are highly desired. Previous biomarker discovery studies have largely focused on the identification of single biomarker signatures, aimed at maximizing prediction accuracy. Here, we present a different approach that identifies multiple biomarkers by simultaneously optimizing their predictive power, number of features, and proximity to the drug target in a protein-protein interaction network. To this end, we incorporated NSGA-II, a fast and elitist multi-objective optimization algorithm that is based on the principle of Pareto optimality, into the biomarker discovery workflow. The method was applied to quantitative phosphoproteome data of 19 non-small cell lung cancer (NSCLC) cell lines from a previous biomarker study. The algorithm successfully identified a total of 77 candidate biomarker signatures predicting response to treatment with dasatinib. Through filtering and similarity clustering, this set was trimmed to four final biomarker signatures, which then were validated on an independent set of breast cancer cell lines. All four candidates reached the same good prediction accuracy (83%) as the originally published biomarker. Although the newly discovered signatures were diverse in their composition and in their size, the central protein of the originally published signature — integrin β4 (ITGB4) — was also present in all four Pareto signatures, confirming its pivotal role in predicting dasatinib response in NSCLC cell lines. In summary, the method presented here allows for a robust and simultaneous identification of multiple multivariate biomarkers that are optimized for prediction performance, size, and relevance. PMID:26083411
The major synthetic evolutionary transitions.
Solé, Ricard
2016-08-19
Evolution is marked by well-defined events involving profound innovations that are known as 'major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These 'synthetic' transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431528
The major synthetic evolutionary transitions.
Solé, Ricard
2016-08-19
Evolution is marked by well-defined events involving profound innovations that are known as 'major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These 'synthetic' transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined.This article is part of the themed issue 'The major synthetic evolutionary transitions'.
Transitions in turbulent rotating convection
NASA Astrophysics Data System (ADS)
Rajaei, Hadi; Alards, Kim; Kunnen, Rudie; Toschi, Federico; Clercx, Herman; Fluid Dynamics Lab Team
2015-11-01
This study aims to explore the flow transition from one state to the other in rotating Rayleigh-Bènard convection using Lagrangian acceleration statistics. 3D particle tracking velocimetry (3D-PTV) is employed in a water-filled cylindrical tank of equal height and diameter. The measurements are performed at the center and close to the top plate at a Rayleigh number Ra = 1.28e9 and Prandtl number Pr = 6.7 for different rotation rates. In parallel, direct numerical simulation (DNS) has been performed to provide detailed information on the boundary layers. We report the acceleration pdfs for different rotation rates and show how the transition from weakly to strongly rotating Rayleigh-Bènard affects the acceleration pdfs in the bulk and boundary layers. We observe that the shapes of the acceleration PDFs as well as the isotropy in the cell center are largely unaffected while crossing the transition point. However, acceleration pdfs at the top show a clear change at the transition point. Using acceleration pdfs and DNS data, we show that the transition between turbulent states is actually a boundary layer transition between Prandtl-Blasius type (typical of non-rotating convection) and Ekman type.
Modelling the transitional boundary layer
NASA Technical Reports Server (NTRS)
Narasimha, R.
1990-01-01
Recent developments in the modelling of the transition zone in the boundary layer are reviewed (the zone being defined as extending from the station where intermittency begins to depart from zero to that where it is nearly unity). The value of using a new non-dimensional spot formation rate parameter, and the importance of allowing for so-called subtransitions within the transition zone, are both stressed. Models do reasonably well in constant pressure 2-dimensional flows, but in the presence of strong pressure gradients further improvements are needed. The linear combination approach works surprisingly well in most cases, but would not be so successful in situations where a purely laminar boundary layer would separate but a transitional one would not. Intermittency-weighted eddy viscosity methods do not predict peak surface parameters well without the introduction of an overshooting transition function whose connection with the spot theory of transition is obscure. Suggestions are made for further work that now appears necessary for developing improved models of the transition zone.
Boundary layer transition studies
NASA Technical Reports Server (NTRS)
Watmuff, Jonathan H.
1995-01-01
A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated
Xu-Dubois, Yi-Chun; Peltier, Julie; Brocheriou, Isabelle; Suberbielle-Boissel, Caroline; Djamali, Arjang; Reese, Shannon; Mooney, Nuala; Keuylian, Zela; Lion, Julien; Ouali, Nacéra; Levy, Pierre P; Jouanneau, Chantal; Rondeau, Eric; Hertig, Alexandre
2016-01-01
Antibody-mediated rejection (ABMR) is a leading cause of allograft loss. Treatment efficacy depends on accurate diagnosis at an early stage. However, sensitive and reliable markers of antibody-endothelium interaction during ABMR are not available for routine use. Using immunohistochemistry, we retrospectively studied the diagnostic value of three markers of endothelial-to-mesenchymal transition (EndMT), fascin1, vimentin, and heat shock protein 47, for ABMR in 53 renal transplant biopsy specimens, including 20 ABMR specimens, 24 cell-mediated rejection specimens, and nine normal grafts. We validated our results in an independent set of 74 unselected biopsy specimens. Endothelial cells of the peritubular capillaries in grafts with ABMR expressed fascin1, vimentin, and heat shock protein 47 strongly, whereas those from normal renal grafts did not. The level of EndMT marker expression was significantly associated with current ABMR criteria, including capillaritis, glomerulitis, peritubular capillary C4d deposition, and donor-specific antibodies. These markers allowed us to identify C4d-negative ABMR and to predict late occurrence of disease. EndMT markers were more specific than capillaritis for the diagnosis and prognosis of ABMR and predicted late (up to 4 years after biopsy) renal graft dysfunction and proteinuria. In the independent set of 74 renal graft biopsy specimens, the EndMT markers for the diagnosis of ABMR had a sensitivity of 100% and a specificity of 85%. Fascin1 expression in peritubular capillaries was also induced in a rat model of ABMR. In conclusion, EndMT markers are a sensitive and reliable diagnostic tool for detecting endothelial activation during ABMR and predicting late loss of allograft function.
Xu-Dubois, Yi-Chun; Peltier, Julie; Brocheriou, Isabelle; Suberbielle-Boissel, Caroline; Djamali, Arjang; Reese, Shannon; Mooney, Nuala; Keuylian, Zela; Lion, Julien; Ouali, Nacéra; Levy, Pierre P; Jouanneau, Chantal; Rondeau, Eric; Hertig, Alexandre
2016-01-01
Antibody-mediated rejection (ABMR) is a leading cause of allograft loss. Treatment efficacy depends on accurate diagnosis at an early stage. However, sensitive and reliable markers of antibody-endothelium interaction during ABMR are not available for routine use. Using immunohistochemistry, we retrospectively studied the diagnostic value of three markers of endothelial-to-mesenchymal transition (EndMT), fascin1, vimentin, and heat shock protein 47, for ABMR in 53 renal transplant biopsy specimens, including 20 ABMR specimens, 24 cell-mediated rejection specimens, and nine normal grafts. We validated our results in an independent set of 74 unselected biopsy specimens. Endothelial cells of the peritubular capillaries in grafts with ABMR expressed fascin1, vimentin, and heat shock protein 47 strongly, whereas those from normal renal grafts did not. The level of EndMT marker expression was significantly associated with current ABMR criteria, including capillaritis, glomerulitis, peritubular capillary C4d deposition, and donor-specific antibodies. These markers allowed us to identify C4d-negative ABMR and to predict late occurrence of disease. EndMT markers were more specific than capillaritis for the diagnosis and prognosis of ABMR and predicted late (up to 4 years after biopsy) renal graft dysfunction and proteinuria. In the independent set of 74 renal graft biopsy specimens, the EndMT markers for the diagnosis of ABMR had a sensitivity of 100% and a specificity of 85%. Fascin1 expression in peritubular capillaries was also induced in a rat model of ABMR. In conclusion, EndMT markers are a sensitive and reliable diagnostic tool for detecting endothelial activation during ABMR and predicting late loss of allograft function. PMID:25995444
Optimized Markov state models for metastable systems
NASA Astrophysics Data System (ADS)
Guarnera, Enrico; Vanden-Eijnden, Eric
2016-07-01
A method is proposed to identify target states that optimize a metastability index amongst a set of trial states and use these target states as milestones (or core sets) to build Markov State Models (MSMs). If the optimized metastability index is small, this automatically guarantees the accuracy of the MSM, in the sense that the transitions between the target milestones is indeed approximately Markovian. The method is simple to implement and use, it does not require that the dynamics on the trial milestones be Markovian, and it also offers the possibility to partition the system's state-space by assigning every trial milestone to the target milestones it is most likely to visit next and to identify transition state regions. Here the method is tested on the Gly-Ala-Gly peptide, where it is shown to correctly identify the expected metastable states in the dihedral angle space of the molecule without a priori information about these states. It is also applied to analyze the folding landscape of the Beta3s mini-protein, where it is shown to identify the folded basin as a connecting hub between an helix-rich region, which is entropically stabilized, and a beta-rich region, which is energetically stabilized and acts as a kinetic trap.
Optimized wavelength selection for molecular absorption thermometry.
An, Xinliang; Caswell, Andrew W; Lipor, John J; Sanders, Scott T
2015-04-01
A differential evolution (DE) algorithm is applied to a recently developed spectroscopic objective function to select wavelengths that optimize the temperature precision of water absorption thermometry. DE reliably finds optima even when many-wavelength sets are chosen from large populations of wavelengths (here 120 000 wavelengths from a spectrum with 0.002 cm(-1) resolution calculated by 16 856 transitions). Here, we study sets of fixed wavelengths in the 7280-7520 cm(-1) range. When optimizing the thermometer for performance within a narrow temperature range, the results confirm that the best temperature precision is obtained if all the available measurement time is split judiciously between the two most temperature-sensitive wavelengths. In the wide temperature range case (thermometer must perform throughout 280-2800 K), we find (1) the best four-wavelength set outperforms the best two-wavelength set by an average factor of 2, and (2) a complete spectrum (all 120 000 wavelengths from 16 856 transitions) is 4.3 times worse than the best two-wavelength set. Key implications for sensor designers include: (1) from the perspective of spectroscopic temperature sensitivity, it is usually sufficient to monitor two or three wavelengths, depending on the sensor's anticipated operating temperature range; and (2) although there is a temperature precision penalty to monitoring a complete spectrum, that penalty may be small enough, particularly at elevated pressure, to justify the complete-spectrum approach in many applications.
Phase Transitions and Gravitational Collapse
NASA Astrophysics Data System (ADS)
Gentile, Nicholas A.
1994-01-01
Results are presented for numerical calculations of gravitational collapses and explosions. Two effects are studied. The first involves aspects of the numerical models used in almost all current gravitational collapse calculations. The second involves phase transitions in the equation of state of dense matter. A (1+1) dimensional general relativistic hydrodynamics code was constructed to investigate both effects. A modification of standard artificial viscosity methods was developed. This extended both the tensor artificial viscosity formulation and the artificial heat conduction formulation to the general relativistic regime. This method shows better results for collapse calculations than the standard scalar artificial viscosity. Numerical collapse calculations were also examined with respect to the number of zones used in the model. These calculations suggest that the number of zones used in current supernova calculations may be insufficient, and that the more sophisticated artificial viscosity methods used may be useful in future core collapse investigations. The second effect studied by this thesis is the impact of phase transitions in dense matter on the results of core collapse in Type 2 supernovae. Two different phase transitions were investigated. The QCD phase transition embodies the prediction of quantum chromodynamics that at high density the constituents of baryonic matter will be free quarks and gluons. The effects on the shock wave formed by core collapse and bounce is studied for various phase transitions. We find that some of the phase transitions modeled significantly increase the shock strength. The second phase transition we study is one from a normal hadronic gas to Q matter. Q matter is a phase of dense baryonic matter that is motivated by soliton models for the nucleus. It has been used to model zero temperature dense matter in static stellar objects, here we extend it to finite temperature, determine the phase transitions with hadronic matter
Transition boiling heat transfer and the film transition regime
NASA Technical Reports Server (NTRS)
Ramilison, J. M.; Lienhard, J. H.
1987-01-01
The Berenson (1960) flat-plate transition-boiling experiment has been recreated with a reduced thermal resistance in the heater, and an improved access to those portions of the transition boiling regime that have a steep negative slope. Tests have been made in Freon-113, acetone, benzene, and n-pentane boiling on horizontal flat copper heaters that have been mirror-polished, 'roughened', or teflon-coated. The resulting data reproduce and clarify certain features observed by Berenson: the modest surface finish dependence of boiling burnout, and the influence of surface chemistry on both the minimum heat flux and the mode of transition boiling, for example. A rational scheme of correlation yields a prediction of the heat flux in what Witte and Lienhard (1982) previously identified as the 'film-transition boiling' region. It is also shown how to calculate the heat flux at the boundary between the pure-film, and the film-transition, boiling regimes, as a function of the advancing contact angle.
Deducing the Kinetics of Protein Synthesis In Vivo from the Transition Rates Measured In Vitro
Rudorf, Sophia; Thommen, Michael; Rodnina, Marina V.; Lipowsky, Reinhard
2014-01-01
The molecular machinery of life relies on complex multistep processes that involve numerous individual transitions, such as molecular association and dissociation steps, chemical reactions, and mechanical movements. The corresponding transition rates can be typically measured in vitro but not in vivo. Here, we develop a general method to deduce the in-vivo rates from their in-vitro values. The method has two basic components. First, we introduce the kinetic distance, a new concept by which we can quantitatively compare the kinetics of a multistep process in different environments. The kinetic distance depends logarithmically on the transition rates and can be interpreted in terms of the underlying free energy barriers. Second, we minimize the kinetic distance between the in-vitro and the in-vivo process, imposing the constraint that the deduced rates reproduce a known global property such as the overall in-vivo speed. In order to demonstrate the predictive power of our method, we apply it to protein synthesis by ribosomes, a key process of gene expression. We describe the latter process by a codon-specific Markov model with three reaction pathways, corresponding to the initial binding of cognate, near-cognate, and non-cognate tRNA, for which we determine all individual transition rates in vitro. We then predict the in-vivo rates by the constrained minimization procedure and validate these rates by three independent sets of in-vivo data, obtained for codon-dependent translation speeds, codon-specific translation dynamics, and missense error frequencies. In all cases, we find good agreement between theory and experiment without adjusting any fit parameter. The deduced in-vivo rates lead to smaller error frequencies than the known in-vitro rates, primarily by an improved initial selection of tRNA. The method introduced here is relatively simple from a computational point of view and can be applied to any biomolecular process, for which we have detailed information
Villa, J. ||; Corchado, J.C. |; Gonzalez-Lafont, A.; Lluch, J.M.; Truhlar, D.G.
1999-07-01
The authors have used canonical variational transition-state theory with multidimensional tunneling contributions (CVT/MT) to calculate 21 kinetic isotope effects (KIE) for the addition of hydrogen atom to ethylene. The potential energies are obtained by variable scaling of external correlation (VSEC). The reorientation of the dividing surface (RODS) algorithm is employed so that the same reaction path can be used for every isotopic substitution. The results show the importance of the tunneling effect for explaining the trends in the KIEs in this almost barrierless reaction. The authors have predicted the regioselectivity for three different isotopically substituted substrates and have shown how the addition to the most substituted carbon is kinetically favored, especially at low temperature. However, their calculations show no cis/trans selectivity for the isotopically substituted ethylene substrate.
Fully localised nonlinear energy growth optimals in pipe flow
NASA Astrophysics Data System (ADS)
Pringle, Chris C. T.; Willis, Ashley P.; Kerswell, Rich R.
2015-06-01
A new, fully localised, energy growth optimal is found over large times and in long pipe domains at a given mass flow rate. This optimal emerges at a threshold disturbance energy below which a nonlinear version of the known (streamwise-independent) linear optimal [P. J. Schmid and D. S. Henningson, "Optimal energy density growth in Hagen-Poiseuille flow," J. Fluid Mech. 277, 192-225 (1994)] is selected and appears to remain the optimal up until the critical energy at which transition is triggered. The form of this optimal is similar to that found in short pipes [Pringle et al., "Minimal seeds for shear flow turbulence: Using nonlinear transient growth to touch the edge of chaos," J. Fluid Mech. 702, 415-443 (2012)], but now with full localisation in the streamwise direction. This fully localised optimal perturbation represents the best approximation yet of the minimal seed (the smallest perturbation which is arbitrarily close to states capable of triggering a turbulent episode) for "real" (laboratory) pipe flows. Dependence of the optimal with respect to several parameters has been computed and establishes that the structure is robust.
Fully localised nonlinear energy growth optimals in pipe flow
Pringle, Chris C. T.; Willis, Ashley P.; Kerswell, Rich R.
2015-06-15
A new, fully localised, energy growth optimal is found over large times and in long pipe domains at a given mass flow rate. This optimal emerges at a threshold disturbance energy below which a nonlinear version of the known (streamwise-independent) linear optimal [P. J. Schmid and D. S. Henningson, “Optimal energy density growth in Hagen-Poiseuille flow,” J. Fluid Mech. 277, 192–225 (1994)] is selected and appears to remain the optimal up until the critical energy at which transition is triggered. The form of this optimal is similar to that found in short pipes [Pringle et al., “Minimal seeds for shear flow turbulence: Using nonlinear transient growth to touch the edge of chaos,” J. Fluid Mech. 702, 415–443 (2012)], but now with full localisation in the streamwise direction. This fully localised optimal perturbation represents the best approximation yet of the minimal seed (the smallest perturbation which is arbitrarily close to states capable of triggering a turbulent episode) for “real” (laboratory) pipe flows. Dependence of the optimal with respect to several parameters has been computed and establishes that the structure is robust.
A new method to calculate reaction paths for conformation transitions of large molecules
NASA Astrophysics Data System (ADS)
Smart, Oliver S.
1994-05-01
Path energy minimization (PEM), a novel method for the generation of a reaction path linking two known conformers of a molecule, is presented. The technique is based on optimizing a function which closely approximates the peak potential energy of a quasi-continuous path between the fixed end points. A transition involving the change in the pucker angle of α-D-xylulofuranose is used as a test case. The method is shown to, be capable of identifying transition state structures and energy barries. The utility of the method is demonstrated by an application to substantial conformational transition of the ion-channel forming polypeptide gramicidin A.
Optimization of Metronidazole Emulgel
Rao, Monica; Sukre, Girish; Aghav, Sheetal; Kumar, Manmeet
2013-01-01
The purpose of the present study was to develop and optimize the emulgel system for MTZ (Metronidazole), a poorly water soluble drug. The pseudoternary phase diagrams were developed for various microemulsion formulations composed of Capmul 908 P, Acconon MC8-2, and propylene glycol. The emulgel was optimized using a three-factor, two-level factorial design, the independent variables selected were Capmul 908 P, and surfactant mixture (Acconon MC8-2 and gelling agent), and the dependent variables (responses) were a cumulative amount of drug permeated across the dialysis membrane in 24 h (Y1) and spreadability (Y2). Mathematical equations and response surface plots were used to relate the dependent and independent variables. The regression equations were generated for responses Y1 and Y2. The statistical validity of the polynomials was established, and optimized formulation factors were selected. Validation of the optimization study with 3 confirmatory runs indicated a high degree of prognostic ability of response surface methodology. Emulgel system of MTZ was developed and optimized using 23 factorial design and could provide an effective treatment against topical infections. PMID:26555982
1998-07-01
GenOpt is a generic optimization program for nonlinear, constrained optimization. For evaluating the objective function, any simulation program that communicates over text files can be coupled to GenOpt without code modification. No analytic properties of the objective function are used by GenOpt. ptimization algorithms and numerical methods can be implemented in a library and shared among users. Gencpt offers an interlace between the optimization algorithm and its kernel to make the implementation of new algorithmsmore » fast and easy. Different algorithms of constrained and unconstrained minimization can be added to a library. Algorithms for approximation derivatives and performing line-search will be implemented. The objective function is evaluated as a black-box function by an external simulation program. The kernel of GenOpt deals with the data I/O, result sotrage and report, interlace to the external simulation program, and error handling. An abstract optimization class offers methods to interface the GenOpt kernel and the optimization algorithm library.« less
Optimization of Heat Exchangers
Ivan Catton
2010-10-01
The objective of this research is to develop tools to design and optimize heat exchangers (HE) and compact heat exchangers (CHE) for intermediate loop heat transport systems found in the very high temperature reator (VHTR) and other Generation IV designs by addressing heat transfer surface augmentation and conjugate modeling. To optimize heat exchanger, a fast running model must be created that will allow for multiple designs to be compared quickly. To model a heat exchanger, volume averaging theory, VAT, is used. VAT allows for the conservation of mass, momentum and energy to be solved for point by point in a 3 dimensional computer model of a heat exchanger. The end product of this project is a computer code that can predict an optimal configuration for a heat exchanger given only a few constraints (input fluids, size, cost, etc.). As VAT computer code can be used to model characteristics )pumping power, temperatures, and cost) of heat exchangers more quickly than traditional CFD or experiment, optimization of every geometric parameter simultaneously can be made. Using design of experiment, DOE and genetric algorithms, GE, to optimize the results of the computer code will improve heat exchanger disign.
NASA Astrophysics Data System (ADS)
Bachmann, Michael
2013-05-01
The simulation of biomolecular structural transitions such as folding and aggregation does not only require adequate models that reflect the key aspects of the cooperative transition behaviour. It is likewise important to employ thermodynamically correct simulation methods and to perform an accurate subsequent statistical analysis of the data obtained in the simulation. The efficient combination of methodology and analysis can be quite sophisticated, but also very instructive in their feedback to a better understanding of the physics of the underlying cooperative processes that drive the conformational transition. We here show that the density of states, which is the central result of multicanonical sampling and any other generalized-ensemble simulation, serves as the optimal basis for the microcanonical statistical analysis of transitions. The microcanonical inflection-point analysis method, which has been introduced for this purpose recently, is a perfect tool for a precise, unique identification and classification of all structural transitions.
Physical implication of transition voltage in organic nano-floating-gate nonvolatile memories
NASA Astrophysics Data System (ADS)
Wang, Shun; Gao, Xu; Zhong, Ya-Nan; Zhang, Zhong-Da; Xu, Jian-Long; Wang, Sui-Dong
2016-07-01
High-performance pentacene-based organic field-effect transistor nonvolatile memories, using polystyrene as a tunneling dielectric and Au nanoparticles as a nano-floating-gate, show parallelogram-like transfer characteristics with a featured transition point. The transition voltage at the transition point corresponds to a threshold electric field in the tunneling dielectric, over which stored electrons in the nano-floating-gate will start to leak out. The transition voltage can be modulated depending on the bias configuration and device structure. For p-type active layers, optimized transition voltage should be on the negative side of but close to the reading voltage, which can simultaneously achieve a high ON/OFF ratio and good memory retention.
NASA Astrophysics Data System (ADS)
Fernandes, Henrique A.; da Silva, Roberto; Santos, Eder D.; Gomes, Paulo F.; Arashiro, Everaldo
2016-08-01
In this paper we revisited the Ziff-Gulari-Barshad model to study its phase transitions and critical exponents through time-dependent Monte Carlo simulations. We use a method proposed recently to locate the nonequilibrium second-order phase transitions and that has been successfully used in systems with defined Hamiltonians and with absorbing states. This method, which is based on optimization of the coefficient of determination of the order parameter, was able to characterize the continuous phase transition of the model, as well as its upper spinodal point, a pseudocritical point located near the discontinuous phase transition. The static critical exponents β , ν∥, and ν⊥, as well as the dynamic critical exponents θ and z for the continuous transition point, were also estimated and are in excellent agreement with results found in literature.
Fernandes, Henrique A; da Silva, Roberto; Santos, Eder D; Gomes, Paulo F; Arashiro, Everaldo
2016-08-01
In this paper we revisited the Ziff-Gulari-Barshad model to study its phase transitions and critical exponents through time-dependent Monte Carlo simulations. We use a method proposed recently to locate the nonequilibrium second-order phase transitions and that has been successfully used in systems with defined Hamiltonians and with absorbing states. This method, which is based on optimization of the coefficient of determination of the order parameter, was able to characterize the continuous phase transition of the model, as well as its upper spinodal point, a pseudocritical point located near the discontinuous phase transition. The static critical exponents β, ν_{∥}, and ν_{⊥}, as well as the dynamic critical exponents θ and z for the continuous transition point, were also estimated and are in excellent agreement with results found in literature. PMID:27627268
Transitions of care in heart failure: a scientific statement from the American Heart Association.
Albert, Nancy M; Barnason, Susan; Deswal, Anita; Hernandez, Adrian; Kociol, Robb; Lee, Eunyoung; Paul, Sara; Ryan, Catherine J; White-Williams, Connie
2015-03-01
In patients with heart failure (HF), use of 30-day rehospitalization as a healthcare metric and increased pressure to provide value-based care compel healthcare providers to improve efficiency and to use an integrated care approach. Transition programs are being used to achieve goals. Transition of care in the context of HF management refers to individual interventions and programs with multiple activities that are designed to improve shifts or transitions from one setting to the next, most often from hospital to home. As transitional care programs become the new normal for patients with chronic HF, it is important to understand the current state of the science of transitional care, as discussed in the available research literature. Of transitional care reports, there was much heterogeneity in research designs, methods, study aims, and program targets, or they were not well described. Often, programs used bundled interventions, making it difficult to discuss the efficiency and effectiveness of specific interventions. Thus, further HF transition care research is needed to ensure best practices related to economically and clinically effective and feasible transition interventions that can be broadly applicable. This statement provides an overview of the complexity of HF management and includes patient, hospital, and healthcare provider barriers to understanding end points that best reflect clinical benefits and to achieving optimal clinical outcomes. The statement describes transitional care interventions and outcomes and discusses implications and recommendations for research and clinical practice to enhance patient-centered outcomes.
Rapid near-optimal aerospace plane trajectory generation and guidance
NASA Technical Reports Server (NTRS)
Corban, J. E.; Calise, A. J.; Flandro, G. A.
1991-01-01
Problems associated with onboard trajectory optimization, propulsion system cycle selection, and the synthesis of guidance laws are addressed for ascent to low earth orbit of an airbreathing, single-stage-to-orbit vehicle. A multicycle propulsion system is assumed that incorporates turbojet, ramjet, scramjet, and rocket engines. An energy state approximation is applied to a singularly perturbed, four-state dynamic model for flight of a point mass over a spherical nonrotating earth. An algorithm is then derived for generating both the fuel-optimal climb profile and the guidance commands required to follow that profile. In particular, analytic switching conditions are derived that, under appropriate assumptions, efficiently govern optimal transition from one propulsion cycle to another. The algorithm proves to be computationally efficient and suitable for real-time implementation. The paper concludes with the presentation of representative numerical results that illustrate the nature of the fuel-optimal climb paths and the tracking performance of the guidance algorithm.
Performance Assessment for Pump-and-Treat Closure or Transition
Truex, Michael J.; Johnson, Christian D.; Becker, Dave J.; Lee, Michelle H.; Nimmons, Michael J.
2015-09-29
A structured performance assessment approach is useful to evaluate pump-and-treat (P&T) groundwater remediation, which has been applied at numerous sites. Consistent with the U.S. Environmental Protection Agency’s Groundwater Road Map, performance assessment during remedy implementation may be needed, and should consider remedy optimization, transition to alternative remedies, or remedy closure. In addition, a recent National Research Council study examined groundwater remediation at complex contaminated sites and concluded that it may be beneficial to evaluate remedy performance and the potential need for transition to alternative approaches at these sites. The intent of this document is to provide a structured approach for assessing P&T performance to support a decision to optimize, transition, or close a P&T remedy. The process presented in this document for gathering information and performing evaluations to support P&T remedy decisions includes use of decision elements to distinguish between potential outcomes of a remedy decision. Case studies are used to augment descriptions of decision elements and to illustrate each type of outcome identified in the performance assessment approach. The document provides references to resources for tools and other guidance relevant to conducting the P&T assessment.
Reliable Transition State Searches Integrated with the Growing String Method.
Zimmerman, Paul
2013-07-01
The growing string method (GSM) is highly useful for locating reaction paths connecting two molecular intermediates. GSM has often been used in a two-step procedure to locate exact transition states (TS), where GSM creates a quality initial structure for a local TS search. This procedure and others like it, however, do not always converge to the desired transition state because the local search is sensitive to the quality of the initial guess. This article describes an integrated technique for simultaneous reaction path and exact transition state search. This is achieved by implementing an eigenvector following optimization algorithm in internal coordinates with Hessian update techniques. After partial convergence of the string, an exact saddle point search begins under the constraint that the maximized eigenmode of the TS node Hessian has significant overlap with the string tangent near the TS. Subsequent optimization maintains connectivity of the string to the TS as well as locks in the TS direction, all but eliminating the possibility that the local search leads to the wrong TS. To verify the robustness of this approach, reaction paths and TSs are found for a benchmark set of more than 100 elementary reactions.
NASA Technical Reports Server (NTRS)
Demmel, J.; Lafferriere, G.
1989-01-01
Consideration is given to the problem of optimal force distribution among three point fingers holding a planar object. A scheme that reduces the nonlinear optimization problem to an easily solved generalized eigenvalue problem is proposed. This scheme generalizes and simplifies results of Ji and Roth (1988). The generalizations include all possible geometric arrangements and extensions to three dimensions and to the case of variable coefficients of friction. For the two-dimensional case with constant coefficients of friction, it is proved that, except for some special cases, the optimal grasping forces (in the sense of minimizing the dependence on friction) are those for which the angles with the corresponding normals are all equal (in absolute value).
Optimal symmetric flight studies
NASA Technical Reports Server (NTRS)
Weston, A. R.; Menon, P. K. A.; Bilimoria, K. D.; Cliff, E. M.; Kelley, H. J.
1985-01-01
Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory.
McMordie Stoughton, Kate; Duan, Xiaoli; Wendel, Emily M.
2013-08-26
This technology evaluation was prepared by Pacific Northwest National Laboratory on behalf of the U.S. Department of Energy’s Federal Energy Management Program (FEMP). ¬The technology evaluation assesses techniques for optimizing reverse osmosis (RO) systems to increase RO system performance and water efficiency. This evaluation provides a general description of RO systems, the influence of RO systems on water use, and key areas where RO systems can be optimized to reduce water and energy consumption. The evaluation is intended to help facility managers at Federal sites understand the basic concepts of the RO process and system optimization options, enabling them to make informed decisions during the system design process for either new projects or recommissioning of existing equipment. This evaluation is focused on commercial-sized RO systems generally treating more than 80 gallons per hour.¬
2013-08-01
This technology evaluation was prepared by Pacific Northwest National Laboratory on behalf of the U.S. Department of Energy’s Federal Energy Management Program (FEMP). The technology evaluation assesses techniques for optimizing reverse osmosis (RO) systems to increase RO system performance and water efficiency. This evaluation provides a general description of RO systems, the influence of RO systems on water use, and key areas where RO systems can be optimized to reduce water and energy consumption. The evaluation is intended to help facility managers at Federal sites understand the basic concepts of the RO process and system optimization options, enabling them to make informed decisions during the system design process for either new projects or recommissioning of existing equipment. This evaluation is focused on commercial-sized RO systems generally treating more than 80 gallons per hour.
Johnson, E.A.; Leung, C.; Schira, J.J.
1983-03-01
A closed loop timing optimization control for an internal combustion engine closed about the instantaneous rotational velocity of the engine's crankshaft is disclosed herein. The optimization control computes from the instantaneous rotational velocity of the engine's crankshaft, a signal indicative of the angle at which the crankshaft has a maximum rotational velocity for the torque impulses imparted to the engine's crankshaft by the burning of an air/fuel mixture in each of the engine's combustion chambers and generates a timing correction signal for each of the engine's combustion chambers. The timing correction signals, applied to the engine timing control, modifies the time at which the ignition signal, injection signals or both are generated such that the rotational velocity of the engine's crankshaft has a maximum value at a predetermined angle for each torque impulse generated optimizing the conversion of the combustion energy to rotational torque.
Fuzzy logic controller optimization
Sepe, Jr., Raymond B; Miller, John Michael
2004-03-23
A method is provided for optimizing a rotating induction machine system fuzzy logic controller. The fuzzy logic controller has at least one input and at least one output. Each input accepts a machine system operating parameter. Each output produces at least one machine system control parameter. The fuzzy logic controller generates each output based on at least one input and on fuzzy logic decision parameters. Optimization begins by obtaining a set of data relating each control parameter to at least one operating parameter for each machine operating region. A model is constructed for each machine operating region based on the machine operating region data obtained. The fuzzy logic controller is simulated with at least one created model in a feedback loop from a fuzzy logic output to a fuzzy logic input. Fuzzy logic decision parameters are optimized based on the simulation.
Electronic transitions of cobalt monoboride
NASA Astrophysics Data System (ADS)
Ng, Y. W.; Pang, H. F.; Cheung, A. S.-C.
2011-11-01
Electronic transition spectrum of cobalt monoboride (CoB) in the visible region between 495 and 560 nm has been observed and analyzed using laser-induced fluorescence spectroscopy. CoB molecule was produced by the reaction of laser-ablated cobalt atom and diborane (B2H6) seeded in argon. Fifteen vibrational bands with resolved rotational structure have been recorded, which included transitions of both Co10B and Co11B isotopic species. Our analysis showed that the observed transition bands are ΔΩ = 0 transitions with Ω″ = 2 and Ω″ = 3 lower states. Four transition systems have been assigned, namely, the [18.1]3Π2-X3Δ2, the [18.3]3Φ3-X3Δ3, the [18.6]3- X3Δ3, and the [19.0]2-X3Δ2 systems. The bond length, ro, of the X 3Δ3 state of CoB is determined to be 1.705 Å. The observed rotational lines showed unresolved hyperfine structure arising from the nuclei, which conforms to the Hund's case (aβ) coupling scheme. This work represents the first experimental investigation of the CoB spectrum.
Transitional care in pediatric urology.
Lambert, Sarah M
2015-04-01
The transition from childhood to adolescence and into adulthood occurs as a natural component of human development. As children progress through school and gain independence, health care practitioners must facilitate a parallel transition from pediatric to adult providers. Modern medicine has succeeded in extending the life expectancy for many children with complex conditions, and adult providers are participating in their medical care through adulthood. Transitioning pediatric urology care to adult urology care is unique to every individual and his or her underlying condition, while the transition process is universal. The objectives of all pediatric urologists include preservation of the kidneys and lower urinary tracts, safe urine storage, safe urine drainage, urinary continence, fertility, sexual function, and genital cosmesis. For some children, these objectives can be attained during childhood, while other children require lifelong maintenance and management. Children with posterior urethral valves, exstrophy-epispadias complex, cloaca, vesicoureteral reflux, neurogenic bladder, disorders of sex development, cancer, hypospadias, nephrolithiasis, undescended testes, varicoceles, ureteropelvic junction obstruction, solitary kidney, and upper tract anomalies all require long-term evaluation and management. The obstacles of altering a patient and caregiver paradigm, locating adult urologists with special expertise, coordinating care with other adult specialties such as nephrology, and navigating the adult health care environment can impede the transition process.
The major synthetic evolutionary transitions
Solé, Ricard
2016-01-01
Evolution is marked by well-defined events involving profound innovations that are known as ‘major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These ‘synthetic’ transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined. This article is part of the themed issue ‘The major synthetic evolutionary transitions’. PMID:27431528
Major transitions in human evolution
Foley, Robert A.; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris
2016-01-01
Evolutionary problems are often considered in terms of ‘origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue ‘Major transitions in human evolution’ throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation—genes, phenotypes and behaviour—integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298461
Electronic Transitions of Ruthenium Monoxide
NASA Astrophysics Data System (ADS)
Wang, Na; Ng, Y. W.; Cheung, A. S.-C.
2013-06-01
The electronic transition spectrum of ruthenium monoxide (RuO) molecule in the spectral region between 545nm to 640nm has been recorded and analyzed using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The RuO molecule was produced by reacting laser- ablated ruthenium atoms with N_{2}O seeded in argon. Nine vibrational bands were recorded and they are identified to be belonging to four electronic transition systems, namely the [18.1]Ω = 4 - X^{5} Δ_4 transition, [16.0]^{5} Φ_5 - X^{5} Δ_4 transition, [18.1]Ω = 3 - X^{5} Δ_3, and [15.8] ^{5} Φ_4 - X^{5} Δ_3 transition. RuO has been determined to have a X^{5} Δ_4 ground state. A least squares fit of the measured rotational lines yielded molecular constants for the ground and the low-lying electronic states. A molecular orbital energy level diagram has been used to help with the assignment of the observed electronic states.
Major transitions in human evolution.
Foley, Robert A; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris
2016-07-01
Evolutionary problems are often considered in terms of 'origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue 'Major transitions in human evolution' throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation-genes, phenotypes and behaviour-integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized.This article is part of the themed issue 'Major transitions in human evolution'. PMID:27298461
Optimization of Combinatorial Mutagenesis
NASA Astrophysics Data System (ADS)
Parker, Andrew S.; Griswold, Karl E.; Bailey-Kellogg, Chris
Protein engineering by combinatorial site-directed mutagenesis evaluates a portion of the sequence space near a target protein, seeking variants with improved properties (stability, activity, immunogenicity, etc.). In order to improve the hit-rate of beneficial variants in such mutagenesis libraries, we develop methods to select optimal positions and corresponding sets of the mutations that will be used, in all combinations, in constructing a library for experimental evaluation. Our approach, OCoM (Optimization of Combinatorial Mutagenesis), encompasses both degenerate oligonucleotides and specified point mutations, and can be directed accordingly by requirements of experimental cost and library size. It evaluates the quality of the resulting library by one- and two-body sequence potentials, averaged over the variants. To ensure that it is not simply recapitulating extant sequences, it balances the quality of a library with an explicit evaluation of the novelty of its members. We show that, despite dealing with a combinatorial set of variants, in our approach the resulting library optimization problem is actually isomorphic to single-variant optimization. By the same token, this means that the two-body sequence potential results in an NP-hard optimization problem. We present an efficient dynamic programming algorithm for the one-body case and a practically-efficient integer programming approach for the general two-body case. We demonstrate the effectiveness of our approach in designing libraries for three different case study proteins targeted by previous combinatorial libraries - a green fluorescent protein, a cytochrome P450, and a beta lactamase. We found that OCoM worked quite efficiently in practice, requiring only 1 hour even for the massive design problem of selecting 18 mutations to generate 107 variants of a 443-residue P450. We demonstrate the general ability of OCoM in enabling the protein engineer to explore and evaluate trade-offs between quality and
NASA Astrophysics Data System (ADS)
Klesh, Andrew T.
This dissertation studies optimal exploration, defined as the collection of information about given objects of interest by a mobile agent (the explorer) using imperfect sensors. The key aspects of exploration are kinematics (which determine how the explorer moves in response to steering commands), energetics (which determine how much energy is consumed by motion and maneuvers), informatics (which determine the rate at which information is collected) and estimation (which determines the states of the objects). These aspects are coupled by the steering decisions of the explorer. We seek to improve exploration by finding trade-offs amongst these couplings and the components of exploration: the Mission, the Path and the Agent. A comprehensive model of exploration is presented that, on one hand, accounts for these couplings and on the other hand is simple enough to allow analysis. This model is utilized to pose and solve several exploration problems where an objective function is to be minimized. Specific functions to be considered are the mission duration and the total energy. These exploration problems are formulated as optimal control problems and necessary conditions for optimality are obtained in the form of two-point boundary value problems. An analysis of these problems reveals characteristics of optimal exploration paths. Several regimes are identified for the optimal paths including the Watchtower, Solar and Drag regime, and several non-dimensional parameters are derived that determine the appropriate regime of travel. The so-called Power Ratio is shown to predict the qualitative features of the optimal paths, provide a metric to evaluate an aircrafts design and determine an aircrafts capability for flying perpetually. Optimal exploration system drivers are identified that provide perspective as to the importance of these various regimes of flight. A bank-to-turn solar-powered aircraft flying at constant altitude on Mars is used as a specific platform for
Distributed Optimization System
Hurtado, John E.; Dohrmann, Clark R.; Robinett, III, Rush D.
2004-11-30
A search system and method for controlling multiple agents to optimize an objective using distributed sensing and cooperative control. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace. The objective can be: chemical sources, temperature sources, radiation sources, light sources, evaders, trespassers, explosive sources, time dependent sources, time independent sources, function surfaces, maximization points, minimization points, and optimal control of a system such as a communication system, an economy, a crane, and a multi-processor computer.
Terascale Optimal PDE Simulations
David Keyes
2009-07-28
The Terascale Optimal PDE Solvers (TOPS) Integrated Software Infrastructure Center (ISIC) was created to develop and implement algorithms and support scientific investigations performed by DOE-sponsored researchers. These simulations often involve the solution of partial differential equations (PDEs) on terascale computers. The TOPS Center researched, developed and deployed an integrated toolkit of open-source, optimal complexity solvers for the nonlinear partial differential equations that arise in many DOE application areas, including fusion, accelerator design, global climate change and reactive chemistry. The algorithms created as part of this project were also designed to reduce current computational bottlenecks by orders of magnitude on terascale computers, enabling scientific simulation on a scale heretofore impossible.
NASA Astrophysics Data System (ADS)
Ouaknin, Gaddiel; Laachi, Nabil; Delaney, Kris; Fredrickson, Glenn; Gibou, Frederic
2016-03-01
Directed self-assembly using block copolymers for positioning vertical interconnect access in integrated circuits relies on the proper shape of a confined domain in which polymers will self-assemble into the targeted design. Finding that shape, i.e., solving the inverse problem, is currently mainly based on trial and error approaches. We introduce a level-set based algorithm that makes use of a shape optimization strategy coupled with self-consistent field theory to solve the inverse problem in an automated way. It is shown that optimal shapes are found for different targeted topologies with accurate placement and distances between the different components.
Optimal Quantum Phase Estimation
Dorner, U.; Smith, B. J.; Lundeen, J. S.; Walmsley, I. A.; Demkowicz-Dobrzanski, R.; Banaszek, K.; Wasilewski, W.
2009-01-30
By using a systematic optimization approach, we determine quantum states of light with definite photon number leading to the best possible precision in optical two-mode interferometry. Our treatment takes into account the experimentally relevant situation of photon losses. Our results thus reveal the benchmark for precision in optical interferometry. Although this boundary is generally worse than the Heisenberg limit, we show that the obtained precision beats the standard quantum limit, thus leading to a significant improvement compared to classical interferometers. We furthermore discuss alternative states and strategies to the optimized states which are easier to generate at the cost of only slightly lower precision.
Space-vehicle trajectories - Optimization
NASA Astrophysics Data System (ADS)
Marec, J. P.
The application of control-theory optimization techniques to the motion of powered vehicles in space is discussed in an analytical review. Problems addressed include the definition of optimal orbital transfer; propulsion-system modeling; parametric optimization and the Hohmann transfer; optimal transfer in general, uniform, and central gravitational fields; and interplanetary rendezvous. Typical numerical results are presented in graphs and briefly characterized.
Optimization on a Network-based Parallel Computer System for Supersonic Laminar Wing Design
NASA Technical Reports Server (NTRS)
Garcia, Joseph A.; Cheung, Samson; Holst, Terry L. (Technical Monitor)
1995-01-01
A set of Computational Fluid Dynamics (CFD) routines and flow transition prediction tools are integrated into a network based parallel numerical optimization routine. Through this optimization routine, the design of a 2-D airfoil and an infinitely swept wing will be studied in order to advance the design cycle capability of supersonic laminar flow wings. The goal of advancing supersonic laminar flow wing design is achieved by wisely choosing the design variables used in the optimization routine. The design variables are represented by the theory of Fourier series and potential theory. These theories, combined with the parallel CFD flow routines and flow transition prediction tools, provide a design space for a global optimal point to be searched. Finally, the parallel optimization routine enables gradient evaluations to be performed in a fast and parallel fashion.
NASA Astrophysics Data System (ADS)
Bohra, Murtaza
Legged rovers are often considered as viable solutions for traversing unknown terrain. This work addresses the optimal locomotion reconfigurability of quadruped rovers, which consists of obtaining optimal locomotion modes, and transitioning between them. A 2D sagittal plane rover model is considered based on a domestic cat. Using a Genetic Algorithm, the gait, pose and control variables that minimize torque or maximize speed are found separately. The optimization approach takes into account the elimination of leg impact, while considering the entire variable spectrum. The optimal solutions are consistent with other works on gait optimization, and are similar to gaits found in quadruped animals as well. An online model-free gait planning framework is also implemented, that is based on Central Pattern Generators is implemented. It is used to generate joint and control trajectories for any arbitrarily varying speed profile, and shown to regulate locomotion transition and speed modulation, both endogenously and continuously.
29 CFR 36.230 - Transition plans.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 1 2010-07-01 2010-07-01 true Transition plans. 36.230 Section 36.230 Labor Office of the... FEDERAL FINANCIAL ASSISTANCE Coverage § 36.230 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
10 CFR 5.230 - Transition plans.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 1 2010-01-01 2010-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...
18 CFR 1317.230 - Transition plans.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Transition plans. 1317... Coverage § 1317.230 Transition plans. (a) Submission of plans. An institution to which § 1317.225 applies... transition plan applicable to all such units, or a separate transition plan applicable to each such unit....
7 CFR 15a.18 - Transition plans.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 1 2012-01-01 2012-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
7 CFR 15a.18 - Transition plans.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 1 2013-01-01 2013-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
7 CFR 15a.18 - Transition plans.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 1 2014-01-01 2014-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
36 CFR 1211.230 - Transition plans.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Transition plans. 1211.230... FINANCIAL ASSISTANCE Coverage § 1211.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...
10 CFR 5.230 - Transition plans.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 10 Energy 1 2014-01-01 2014-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...
7 CFR 15a.18 - Transition plans.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 1 2011-01-01 2011-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
29 CFR 36.230 - Transition plans.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 29 Labor 1 2014-07-01 2013-07-01 true Transition plans. 36.230 Section 36.230 Labor Office of the... FEDERAL FINANCIAL ASSISTANCE Coverage § 36.230 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...
32 CFR 196.230 - Transition plans.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 32 National Defense 2 2013-07-01 2013-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...
36 CFR 1211.230 - Transition plans.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Transition plans. 1211.230... FINANCIAL ASSISTANCE Coverage § 1211.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...
32 CFR 196.230 - Transition plans.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 32 National Defense 2 2012-07-01 2012-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...
44 CFR 19.230 - Transition plans.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Transition plans. 19.230... RECEIVING FEDERAL FINANCIAL ASSISTANCE Coverage § 19.230 Transition plans. (a) Submission of plans. An... submit either a single transition plan applicable to all such units, or a separate transition...
45 CFR 2555.230 - Transition plans.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 45 Public Welfare 4 2012-10-01 2012-10-01 false Transition plans. 2555.230 Section 2555.230 Public... Coverage § 2555.230 Transition plans. (a) Submission of plans. An institution to which § 2555.225 applies... transition plan applicable to all such units, or a separate transition plan applicable to each such unit....
32 CFR 196.230 - Transition plans.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 32 National Defense 2 2011-07-01 2011-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...
10 CFR 5.230 - Transition plans.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 10 Energy 1 2011-01-01 2011-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...
33 CFR 401.74 - Transit declaration.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Transit declaration. 401.74... Transit declaration. (a) Seaway Transit Declaration Form (Cargo and Passenger) shall be forwarded to the... ships, within fourteen days after the vessel enters the Seaway on any upbound or downbound transit....
33 CFR 401.74 - Transit declaration.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Transit declaration. 401.74... Transit declaration. (a) A Seaway Transit Declaration Form (Cargo and Passenger) shall be forwarded to the... bound transit. The form may be obtained from the St. Lawrence Management Corporation, 151 Ecluse...
Individualized Transition Plans (ITP): A National Perspective.
ERIC Educational Resources Information Center
Repetto, Jeanne B.; And Others
1990-01-01
Information concerning implementation of Individualized Transition Plans (ITP) was collected from 46 states and analyzed to determine documentation used in transition planning, relationship between the ITP and Individualized Education Programs, age for beginning transition planning, individuals involved in transition planning, and issues addressed…
A Plan for Dealing with Transition.
ERIC Educational Resources Information Center
Arin-Krupp, Judy
1984-01-01
The author describes her plan for dealing with life transitions. The plan has three steps. First, the individual in transition must accurately perceive the situation; second, respond to the situation, change, or transition; and third, reassess his or her perception of the transition. (CT)
24 CFR 990.225 - Transition determination.
Code of Federal Regulations, 2013 CFR
2013-04-01
... DEVELOPMENT THE PUBLIC HOUSING OPERATING FUND PROGRAM Transition Policy and Transition Funding § 990.225 Transition determination. The determination of the amount and period of the transition funding shall be based on the difference in subsidy levels between the formula set forth in this part and the formula...
24 CFR 990.225 - Transition determination.
Code of Federal Regulations, 2012 CFR
2012-04-01
... DEVELOPMENT THE PUBLIC HOUSING OPERATING FUND PROGRAM Transition Policy and Transition Funding § 990.225 Transition determination. The determination of the amount and period of the transition funding shall be based on the difference in subsidy levels between the formula set forth in this part and the formula...
Family-Directed Transition Planning Guide.
ERIC Educational Resources Information Center
Colorado State Dept. of Education, Denver. Div. of Special Education Services.
This guide to family-directed transition planning is intended to help parents and students with disabilities take leading roles in the process of transition from school to post-school activities. First, a letter to families examines the challenge of change and the transition process. Section 2 examines regulations that affect transition planning,…
Transition metals in superheat melts
NASA Technical Reports Server (NTRS)
Jakes, Petr; Wolfbauer, Michael-Patrick
1993-01-01
A series of experiments with silicate melts doped with transition element oxides was carried out at atmospheric pressures of inert gas at temperatures exceeding liquidus. As predicted from the shape of fO2 buffer curves in T-fO2 diagrams the reducing conditions for a particular oxide-metal pair can be achieved through the T increase if the released oxygen is continuously removed. Experimental studies suggest that transition metals such as Cr or V behave as siderophile elements at temperatures exceeding liquidus temperatures if the system is not buffered by the presence of other oxide of more siderophile element. For example the presence of FeO prevents the reduction of Cr2O3. The sequence of decreasing siderophility of transition elements at superheat conditions (Mo, Ni, Fe, Cr) matches the decreasing degree of depletion of siderophile elements in mantle rocks as compared to chondrites.
Transitions in individuality through symbiosis.
Estrela, Sylvie; Kerr, Benjamin; Morris, J Jeffrey
2016-06-01
When a more complex, functionally integrated entity emerges from the association of simpler, initially independent entities, a major evolutionary transition has occurred. Transitions that result from the association of different species include the evolution of the eukaryotic cell and some obligate mutualisms. Recent studies are revolutionizing our understanding of how these intimate interspecific associations come to be, revealing how and to what extent each partner contributes to the relationship, and how partners mediate conflict. Here, we review work on the evolution of mutualistic symbioses in the context of transitions in individuality and highlight how a better mechanistic understanding of the ecological drivers of host-symbiont interdependencies can help elucidate the evolutionary path to symbiotic organismality. PMID:27131019
Sliding Over a Phase Transition
NASA Astrophysics Data System (ADS)
Tosatti, Erio; Benassi, Andrea; Vanossi, Andrea; Santoro, Giuseppe E.
2011-03-01
The frictional response experienced by a stick-slip slider when a phase transition occurs in the underlying solid substrate is a potentially exciting, poorly explored problem. We show, based on 2-dimensional simulations modeling the sliding of a nanotip, that indeed friction may be heavily affected by a continuous structural transition. First, friction turns nonmonotonic as temperature crosses the transition, peaking at the critical temperature Tc where fluctuations are strongest. Second, below Tc friction depends upon order parameter directions, and is much larger for those where the frictional slip can cause a local flip. This may open a route towards control of atomic scale friction by switching the order parameter direction by an external field or strain, with possible application to e.g., displacive ferroelectrics such as BaTi O3 , as well as ferro- and antiferro-distortive materials. Supported by project ESF FANAS/AFRI sponsored by the Italian Research Council (CNR).
Transition in Internally Heated Convection
NASA Astrophysics Data System (ADS)
Tasaka, Yuji; Yanagisawa, Takatoshi
2005-11-01
Natural convection induced by internal heat generation in a shallow fluid layer was investigated experimentally. Internal heat generation was realized by passing electric current through ionic liquid. Kalliroscope flakes and thermo-chromic liquid crystal were utilized to clarify a transition of the convection with respect to the Rayleigh number, RI. Visualized flow pattern at higher Rayleigh number show two types of deformed cell shape, double cell structure, which has a small cell in a large cell, and spoke like cell structure, where descending flow neat the center of a cell spread like a spoke. Visualized temperature field was converted to temperature field in order to investigate the transition quantitatively. Variation of horizontal temperature fluctuation with respect to RI may show critical Rayleigh number for the transition.
Transitions in individuality through symbiosis.
Estrela, Sylvie; Kerr, Benjamin; Morris, J Jeffrey
2016-06-01
When a more complex, functionally integrated entity emerges from the association of simpler, initially independent entities, a major evolutionary transition has occurred. Transitions that result from the association of different species include the evolution of the eukaryotic cell and some obligate mutualisms. Recent studies are revolutionizing our understanding of how these intimate interspecific associations come to be, revealing how and to what extent each partner contributes to the relationship, and how partners mediate conflict. Here, we review work on the evolution of mutualistic symbioses in the context of transitions in individuality and highlight how a better mechanistic understanding of the ecological drivers of host-symbiont interdependencies can help elucidate the evolutionary path to symbiotic organismality.
Electronic transitions of iridium monophosphide
NASA Astrophysics Data System (ADS)
Yang, M.; Chan, Man-Chor; Cheung, A. S.-C.
2016-05-01
Laser induced fluorescence spectrum of IrP in the near infrared spectral region between 720 and 820 nm has been recorded and analyzed. Six vibrational bands with resolved rotational structure for both 191IrP and 193IrP were analyzed, they have been grouped into three new electronic transitions: the [13.6] Ω = 2 - a3Π2, the [12.3]1Π1-X1Σ+, and the [12.7]1Π1-X1Σ+ transitions. Ab initio calculation results were used to aid the assignment of the observed transitions. A new triplet state has been observed for the first time. The observed electronic states of IrP are compared with those of the isovalent IrN molecule.
ERIC Educational Resources Information Center
Dawson, Michelle; Pooley, Julie Ann
2013-01-01
Throughout our lifespan we face many challenges which are often referred to as transitions. The move to university is one such transition which may place individuals at risk of suffering ongoing significant life stress, anxiety and uncertainty. Optimism, promotion of independent functioning (PIF), promotion of volitional functioning (PVF) and…
The migration transition in Malaysia.
Lim, L L
1996-01-01
"Exploring the unique experience of migration transition in Malaysia, this paper identifies the turning points in relation to the level and nature of economic and labor market developments in Malaysia. Examining the development dynamics that mark the passage from exporting labor to depending on foreign labor, the paper concludes that such dynamics are influenced not only by economic but also sociocultural, demographic and policy factors. Several lessons from the Malaysian experience are drawn at the end to be utilized by other countries that still have to reach the turning points of the migration transition." PMID:12320775
Theoretical Studies of Atomic Transitions
Charlotte Froese Fischer
2005-07-08
Atomic structure calculations were performed for properties such as energy levels, binding energies, transition probabilities, lifetimes, hyperfine structure, and isotope shifts. Accurate computational procedures were devised so that properties could be predicted even when they could not be obtained from experiment, and to assist in the identification of observed data. The method used was the multiconfiguration Hartree-Fock (MCHF) method, optionally corrected for relativistic effects in the Breit-Pauli approximation. Fully relativistic Dirac-Fock calculations also were performed using the GRASP code A database of energy levels, lifetimes, and transition probabilities was designed and implemented and, at present, includes many results for Be-like to Ar-like.
Space Station transition through Spacelab
NASA Technical Reports Server (NTRS)
Craft, Harry G., Jr.; Wicks, Thomas G.
1990-01-01
It is appropriate that NASA's Office of Space Science and Application's science management structures and processes that have proven successful on Spacelab be applied and extrapolated to Space Station utilization, wherever practical. Spacelab has many similarities and complementary aspects to Space Station Freedom. An understanding of the similarities and differences between Spacelab and Space Station is necessary in order to understand how to transition from Spacelab to Space Station. These relationships are discussed herein as well as issues which must be dealt with and approaches for transition and evolution from Spacelab to Space Station.
William Crabtree's Venus transit observation
NASA Astrophysics Data System (ADS)
Kollerstrom, Nicholas
2005-04-01
The close collaboration between the two North-country astronomers Jeremiah Horrocks and William Crabtree gave them special insight into the new astronomy published by the recently-deceased Kepler, whereby Horrocks became the only person to apprehend that the Rudolphine tables were in fact predicting a Venus transit in 1639. This paper focuses especially upon William Crabtree's role and contribution. A comparison is made with an earlier, unsuccessful endeavour by these two concerning a possible transit of Mercury. Much of the record of their work was lost during the civil war. Finally, thanks to Christiaan Huygens, Horrock's manuscript was published by Johannes Hevelius in Danzig, in 1662.
Toward Optimal Transport Networks
NASA Technical Reports Server (NTRS)
Alexandrov, Natalia; Kincaid, Rex K.; Vargo, Erik P.
2008-01-01
Strictly evolutionary approaches to improving the air transport system a highly complex network of interacting systems no longer suffice in the face of demand that is projected to double or triple in the near future. Thus evolutionary approaches should be augmented with active design methods. The ability to actively design, optimize and control a system presupposes the existence of predictive modeling and reasonably well-defined functional dependences between the controllable variables of the system and objective and constraint functions for optimization. Following recent advances in the studies of the effects of network topology structure on dynamics, we investigate the performance of dynamic processes on transport networks as a function of the first nontrivial eigenvalue of the network's Laplacian, which, in turn, is a function of the network s connectivity and modularity. The last two characteristics can be controlled and tuned via optimization. We consider design optimization problem formulations. We have developed a flexible simulation of network topology coupled with flows on the network for use as a platform for computational experiments.
ERIC Educational Resources Information Center
Homan, Michael; Worley, Penny
This course syllabus describes methods for optimizing online searching, using as an example searching on the National Library of Medicine (NLM) online system. Four major activities considered are the online interview, query analysis and search planning, online interaction, and post-search analysis. Within the context of these activities, concepts…
NASA Astrophysics Data System (ADS)
Huang, Siendong
2009-11-01
The nonlocality of quantum states on a bipartite system \\mathcal {A+B} is tested by comparing probabilistic outcomes of two local observables of different subsystems. For a fixed observable A of the subsystem \\mathcal {A,} its optimal approximate double A' of the other system \\mathcal {B} is defined such that the probabilistic outcomes of A' are almost similar to those of the fixed observable A. The case of σ-finite standard von Neumann algebras is considered and the optimal approximate double A' of an observable A is explicitly determined. The connection between optimal approximate doubles and quantum correlations is explained. Inspired by quantum states with perfect correlation, like Einstein-Podolsky-Rosen states and Bohm states, the nonlocality power of an observable A for general quantum states is defined as the similarity that the outcomes of A look like the properties of the subsystem \\mathcal {B} corresponding to A'. As an application of optimal approximate doubles, maximal Bell correlation of a pure entangled state on \\mathcal {B}(\\mathbb {C}^{2})\\otimes \\mathcal {B}(\\mathbb {C}^{2}) is found explicitly.
Optimization of digital designs
NASA Technical Reports Server (NTRS)
Whitaker, Sterling R. (Inventor); Miles, Lowell H. (Inventor)
2009-01-01
An application specific integrated circuit is optimized by translating a first representation of its digital design to a second representation. The second representation includes multiple syntactic expressions that admit a representation of a higher-order function of base Boolean values. The syntactic expressions are manipulated to form a third representation of the digital design.
Fourier Series Optimization Opportunity
ERIC Educational Resources Information Center
Winkel, Brian
2008-01-01
This note discusses the introduction of Fourier series as an immediate application of optimization of a function of more than one variable. Specifically, it is shown how the study of Fourier series can be motivated to enrich a multivariable calculus class. This is done through discovery learning and use of technology wherein students build the…
ERIC Educational Resources Information Center
Cody, Martin L.
1974-01-01
Discusses the optimality of natural selection, ways of testing for optimum solutions to problems of time - or energy-allocation in nature, optimum patterns in spatial distribution and diet breadth, and how best to travel over a feeding area so that food intake is maximized. (JR)
Optimal ciliary beating patterns
NASA Astrophysics Data System (ADS)
Vilfan, Andrej; Osterman, Natan
2011-11-01
We introduce a measure for energetic efficiency of single or collective biological cilia. We define the efficiency of a single cilium as Q2 / P , where Q is the volume flow rate of the pumped fluid and P is the dissipated power. For ciliary arrays, we define it as (ρQ) 2 / (ρP) , with ρ denoting the surface density of cilia. We then numerically determine the optimal beating patterns according to this criterion. For a single cilium optimization leads to curly, somewhat counterintuitive patterns. But when looking at a densely ciliated surface, the optimal patterns become remarkably similar to what is observed in microorganisms like Paramecium. The optimal beating pattern then consists of a fast effective stroke and a slow sweeping recovery stroke. Metachronal waves lead to a significantly higher efficiency than synchronous beating. Efficiency also increases with an increasing density of cilia up to the point where crowding becomes a problem. We finally relate the pumping efficiency of cilia to the swimming efficiency of a spherical microorganism and show that the experimentally estimated efficiency of Paramecium is surprisingly close to the theoretically possible optimum.
Optimizing Conferencing Freeware
ERIC Educational Resources Information Center
Baggaley, Jon; Klaas, Jim; Wark, Norine; Depow, Jim
2005-01-01
The increasing range of options provided by two popular conferencing freeware products, "Yahoo Messenger" and "MSN Messenger," are discussed. Each tool contains features designed primarily for entertainment purposes, which can be customized for use in online education. This report provides suggestions for optimizing the educational potential of…
Accelerating Lead Compound Optimization.
Poh, Alissa
2016-04-01
Chemists at The Scripps Research Institute in La Jolla, CA, and Pfizer's La Jolla Laboratories have devised a new way to rapidly synthesize strained-ring structures, which are increasingly favored to optimize potential drugs. With this method, strain-release amination, Pfizer researchers were able to produce sufficient quantities of a particular structure they needed to evaluate a promising cancer drug candidate.
ERIC Educational Resources Information Center
Simmons, Joseph P.; Massey, Cade
2012-01-01
Is optimism real, or are optimistic forecasts just cheap talk? To help answer this question, we investigated whether optimistic predictions persist in the face of large incentives to be accurate. We asked National Football League football fans to predict the winner of a single game. Roughly half (the partisans) predicted a game involving their…
ERIC Educational Resources Information Center
Rebilas, Krzysztof
2013-01-01
Consider a skier who goes down a takeoff ramp, attains a speed "V", and jumps, attempting to land as far as possible down the hill below (Fig. 1). At the moment of takeoff the angle between the skier's velocity and the horizontal is [alpha]. What is the optimal angle [alpha] that makes the jump the longest possible for the fixed magnitude of the…
Optimization of Systran System.
ERIC Educational Resources Information Center
Toma, Peter P.; And Others
This report describes an optimization phase of the SYSTRAN (System Translation) machine translation technique. The most distinctive characteristic of SYSTRAN is the absence of pre-editing; the program reads tapes containing raw and unedited Russian texts, carries out dictionary and table lookups, performs all syntactic analysis procedures, and…
Optimization in Cardiovascular Modeling
NASA Astrophysics Data System (ADS)
Marsden, Alison L.
2014-01-01
Fluid mechanics plays a key role in the development, progression, and treatment of cardiovascular disease. Advances in imaging methods and patient-specific modeling now reveal increasingly detailed information about blood flow patterns in health and disease. Building on these tools, there is now an opportunity to couple blood flow simulation with optimization algorithms to improve the design of surgeries and devices, incorporating more information about the flow physics in the design process to augment current medical knowledge. In doing so, a major challenge is the need for efficient optimization tools that are appropriate for unsteady fluid mechanics problems, particularly for the optimization of complex patient-specific models in the presence of uncertainty. This article reviews the state of the art in optimization tools for virtual surgery, device design, and model parameter identification in cardiovascular flow and mechanobiology applications. In particular, it reviews trade-offs between traditional gradient-based methods and derivative-free approaches, as well as the need to incorporate uncertainties. Key future challenges are outlined, which extend to the incorporation of biological response and the customization of surgeries and devices for individual patients.
Flex Fuel Optimized SI and HCCI Engine
Zhu, Guoming; Schock, Harold; Yang, Xiaojian; Huisjen, Andrew; Stuecken, Tom; Moran, Kevin; Zhen, Ron; Zhang, Shupeng
2013-09-30
The central objective of the proposed work is to demonstrate an HCCI (homogeneous charge compression ignition) capable SI (spark ignited) engine that is capable of fast and smooth mode transition between SI and HCCI combustion modes. The model-based control technique was used to develop and validate the proposed control strategy for the fast and smooth combustion mode transition based upon the developed control-oriented engine; and an HCCI capable SI engine was designed and constructed using production ready two-step valve-train with electrical variable valve timing actuating system. Finally, smooth combustion mode transition was demonstrated on a metal engine within eight engine cycles. The Chrysler turbocharged 2.0L I4 direct injection engine was selected as the base engine for the project and the engine was modified to fit the two-step valve with electrical variable valve timing actuating system. To develop the model-based control strategy for stable HCCI combustion and smooth combustion mode transition between SI and HCCI combustion, a control-oriented real-time engine model was developed and implemented into the MSU HIL (hardware-in-the-loop) simulation environment. The developed model was used to study the engine actuating system requirement for the smooth and fast combustion mode transition and to develop the proposed mode transition control strategy. Finally, a single cylinder optical engine was designed and fabricated for studying the HCCI combustion characteristics. Optical engine combustion tests were conducted in both SI and HCCI combustion modes and the test results were used to calibrate the developed control-oriented engine model. Intensive GT-Power simulations were conducted to determine the optimal valve lift (high and low) and the cam phasing range. Delphi was selected to be the supplier for the two-step valve-train and Denso to be the electrical variable valve timing system supplier. A test bench was constructed to develop control strategies for
Dynamic Transitions of Generalized Burgers Equation
NASA Astrophysics Data System (ADS)
Li, Limei; Ong, Kiah Wah
2016-03-01
In this article, we study the dynamic transition for the one dimensional generalized Burgers equation with periodic boundary condition. The types of transition are dictated by the sign of an explicitly given parameter b, which is derived using the dynamic transition theory developed by Ma and Wang (Phase transition dynamics. Springer, New York, 2014). The rigorous result demonstrates clearly the types of dynamics transition in terms of length scale l, dispersive parameter δ and viscosity ν.
Optimal control of complex atomic quantum systems
NASA Astrophysics Data System (ADS)
van Frank, S.; Bonneau, M.; Schmiedmayer, J.; Hild, S.; Gross, C.; Cheneau, M.; Bloch, I.; Pichler, T.; Negretti, A.; Calarco, T.; Montangero, S.
2016-10-01
Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications. Indeed, it can engineer protocols at the quantum speed limit – the fastest achievable timescale of the transformation. Here, we demonstrate such potential by computing theoretically and verifying experimentally the optimal transformations in two very different interacting systems: the coherent manipulation of motional states of an atomic Bose-Einstein condensate and the crossing of a quantum phase transition in small systems of cold atoms in optical lattices. We also show that such processes are robust with respect to perturbations, including temperature and atom number fluctuations.
Evolutionary strategies for solving optimization problems
NASA Astrophysics Data System (ADS)
Ebeling, Werner; Reimann, Axel; Molgedey, Lutz
We will give a survey of applications of thermodynamically and biologically oriented evolutionary strategies for optimization problems. Primarily, we investigate the solution of discrete optimization problems, most of combinatorial type, using a certain class of coupled differential equations. The problem is to find the minimum on a large set of real numbers (the potential) Ui, defined on the integer set i = 1 ...s, where s is an extremely large nu mber. The stationary states of the system correspond to relative optima on the discrete set. First, several elementary evolutionary strategies are described by simple deterministic equations, leading to a high-dimensional system of coupled differential equations. The known equations for thermodynamic search processes and for simple models of biological evolution are unified by defining a two-parameter family of equations which embed both cases. The unified equations model mixed Boltzmann/Darwin- strategies including basic elements of thermodynamical and biological evolution as well. In a next step a master equation model in the occupation number space is defined. We investigate the transition probabilities and the convergence properties using tools from the theory of stochastic processes. Several examples are analyzed. In particular we study the optimization of theoretical model sequences with simple valuation rules. In order to demonstrate that the strategies developed here may also be used to investigate realistic problems we present an example application to RNA folding (search for a minimum free energy configuration).
Optimal control of complex atomic quantum systems
van Frank, S.; Bonneau, M.; Schmiedmayer, J.; Hild, S.; Gross, C.; Cheneau, M.; Bloch, I.; Pichler, T.; Negretti, A.; Calarco, T.; Montangero, S.
2016-01-01
Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications. Indeed, it can engineer protocols at the quantum speed limit – the fastest achievable timescale of the transformation. Here, we demonstrate such potential by computing theoretically and verifying experimentally the optimal transformations in two very different interacting systems: the coherent manipulation of motional states of an atomic Bose-Einstein condensate and the crossing of a quantum phase transition in small systems of cold atoms in optical lattices. We also show that such processes are robust with respect to perturbations, including temperature and atom number fluctuations. PMID:27725688
Optimal GENCO bidding strategy
NASA Astrophysics Data System (ADS)
Gao, Feng
Electricity industries worldwide are undergoing a period of profound upheaval. The conventional vertically integrated mechanism is being replaced by a competitive market environment. Generation companies have incentives to apply novel technologies to lower production costs, for example: Combined Cycle units. Economic dispatch with Combined Cycle units becomes a non-convex optimization problem, which is difficult if not impossible to solve by conventional methods. Several techniques are proposed here: Mixed Integer Linear Programming, a hybrid method, as well as Evolutionary Algorithms. Evolutionary Algorithms share a common mechanism, stochastic searching per generation. The stochastic property makes evolutionary algorithms robust and adaptive enough to solve a non-convex optimization problem. This research implements GA, EP, and PS algorithms for economic dispatch with Combined Cycle units, and makes a comparison with classical Mixed Integer Linear Programming. The electricity market equilibrium model not only helps Independent System Operator/Regulator analyze market performance and market power, but also provides Market Participants the ability to build optimal bidding strategies based on Microeconomics analysis. Supply Function Equilibrium (SFE) is attractive compared to traditional models. This research identifies a proper SFE model, which can be applied to a multiple period situation. The equilibrium condition using discrete time optimal control is then developed for fuel resource constraints. Finally, the research discusses the issues of multiple equilibria and mixed strategies, which are caused by the transmission network. Additionally, an advantage of the proposed model for merchant transmission planning is discussed. A market simulator is a valuable training and evaluation tool to assist sellers, buyers, and regulators to understand market performance and make better decisions. A traditional optimization model may not be enough to consider the distributed
Raman transitions between hyperfine clock states in a magnetic trap
NASA Astrophysics Data System (ADS)
Naber, J. B.; Torralbo-Campo, L.; Hubert, T.; Spreeuw, R. J. C.
2016-07-01
We present our experimental investigation of an optical Raman transition between the magnetic clock states of 87Rb in an atom chip magnetic trap. The transfer of atomic population is induced by a pair of diode lasers which couple the two clock states off-resonantly to an intermediate state manifold. This transition is subject to destructive interference of two excitation paths, which leads to a reduction of the effective two-photon Rabi frequency. Furthermore, we find that the transition frequency is highly sensitive to the intensity ratio of the diode lasers. Our results are well described in terms of light shifts in the multilevel structure of 87Rb. The differential light shifts vanish at an optimal intensity ratio, which we observe as a narrowing of the transition linewidth. We also observe the temporal dynamics of the population transfer and find good agreement with a model based on the system's master equation and a Gaussian laser beam profile. Finally, we identify several sources of decoherence in our system, and discuss possible improvements.
THE LUPUS TRANSIT SURVEY FOR HOT JUPITERS: RESULTS AND LESSONS
Bayliss, Daniel D. R.; Sackett, Penny D.; Weldrake, David T. F.; Tingley, Brandon W. E-mail: penny.sackett@anu.edu.au E-mail: btingley@iac.es
2009-05-15
We present the results of a deep, wide-field transit survey targeting 'Hot Jupiter' planets in the Lupus region of the Galactic plane conducted over 53 nights concentrated in two epochs separated by a year. Using the Australian National University 40-inch telescope at Siding Spring Observatory (SSO), the survey covered a 0.66 deg{sup 2} region close to the Galactic plane (b = 11{sup 0}) and monitored a total of 110,372 stars (15.0 {<=} V {<=} 22.0). Using difference imaging photometry, 16,134 light curves with a photometric precision of {sigma} < 0.025 mag were obtained. These light curves were searched for transits, and four candidates were detected that displayed low-amplitude variability consistent with a transiting giant planet. Further investigations, including spectral typing and radial velocity measurements for some candidates, revealed that of the four, one is a true planetary companion (Lupus-TR-3), two are blended systems (Lupus-TR-1 and 4), and one is a binary (Lupus-TR-2). The results of this successful survey are instructive for optimizing the observational strategy and follow-up procedure for deep searches for transiting planets, including an upcoming survey using the SkyMapper telescope at SSO.
Partial information, market efficiency, and anomalous continuous phase transition
NASA Astrophysics Data System (ADS)
Yang, Guang; Zheng, Wenzhi; Huang, Jiping
2014-04-01
It is a common belief in economics and social science that if there is more information available for agents to gather in a human system, the system can become more efficient. The belief can be easily understood according to the well-known efficient market hypothesis. In this work, we attempt to challenge this belief by investigating a complex adaptive system, which is modeled by a market-directed resource-allocation game with a directed random network. We conduct a series of controlled human experiments in the laboratory to show the reliability of the model design. As a result, we find that even under a small information concentration, the system can still almost reach the optimal (balanced) state. Furthermore, the ensemble average of the system’s fluctuation level goes through a continuous phase transition. This behavior means that in the second phase if too much information is shared among agents, the system’s stability will be harmed instead, which differs from the belief mentioned above. Also, at the transition point, the ensemble fluctuations of the fluctuation level remain at a low value. This phenomenon is in contrast to the textbook knowledge about continuous phase transitions in traditional physical systems, namely, fluctuations will rise abnormally around a transition point since the correlation length becomes infinite. Thus, this work is of potential value to a variety of fields, such as physics, economics, complexity science, and artificial intelligence.
Transitioning premature infants supine: state of the science.
McMullen, Sherri L
2013-01-01
Safe infant sleep has been the focus of two decades of research. Improving supine sleep position in infants has coincided with a reduction in sudden infant death syndrome (SIDS). Premature infants spend time prone while hospitalized to promote appropriate growth and development; however, after hospitalization, infants should be positioned supine to reduce the risk of SIDS. Research has not been conducted on the optimal timing of transitioning the premature infant supine prior to hospital discharge. Infants transitioned too early are at risk for developmental delays, and infants not transitioned prior to discharge are at risk for being positioned in a nonsupine position, thereby increasing the risk of SIDS. Parents can observe appropriate role modeling of their infant while hospitalized and potentially improve the rate of supine sleep after discharge to reduce the risk of SIDS. This review explores the current literature on transitioning the premature infant to the supine position prior to hospital discharge to improve evidence-based practice and potentially further reducing the SIDS rate. PMID:23060326
(Too) optimistic about optimism: the belief that optimism improves performance.
Tenney, Elizabeth R; Logg, Jennifer M; Moore, Don A
2015-03-01
A series of experiments investigated why people value optimism and whether they are right to do so. In Experiments 1A and 1B, participants prescribed more optimism for someone implementing decisions than for someone deliberating, indicating that people prescribe optimism selectively, when it can affect performance. Furthermore, participants believed optimism improved outcomes when a person's actions had considerable, rather than little, influence over the outcome (Experiment 2). Experiments 3 and 4 tested the accuracy of this belief; optimism improved persistence, but it did not improve performance as much as participants expected. Experiments 5A and 5B found that participants overestimated the relationship between optimism and performance even when their focus was not on optimism exclusively. In summary, people prescribe optimism when they believe it has the opportunity to improve the chance of success-unfortunately, people may be overly optimistic about just how much optimism can do.
NASA Astrophysics Data System (ADS)
Spagnolie, Saverio E.; Lauga, Eric
2010-03-01
Motile eukaryotic cells propel themselves in viscous fluids by passing waves of bending deformation down their flagella. An infinitely long flagellum achieves a hydrodynamically optimal low-Reynolds number locomotion when the angle between its local tangent and the swimming direction remains constant along its length. Optimal flagella therefore adopt the shape of a helix in three dimensions (smooth) and that of a sawtooth in two dimensions (nonsmooth). Physically, biological organisms (or engineered microswimmers) must expend internal energy in order to produce the waves of deformation responsible for the motion. Here we propose a physically motivated derivation of the optimal flagellum shape. We determine analytically and numerically the shape of the flagellar wave which leads to the fastest swimming for a given appropriately defined energetic expenditure. Our novel approach is to define an energy which includes not only the work against the surrounding fluid, but also (1) the energy stored elastically in the bending of the flagellum, (2) the energy stored elastically in the internal sliding of the polymeric filaments which are responsible for the generation of the bending waves (microtubules), and (3) the viscous dissipation due to the presence of an internal fluid. This approach regularizes the optimal sawtooth shape for two-dimensional deformation at the expense of a small loss in hydrodynamic efficiency. The optimal waveforms of finite-size flagella are shown to depend on a competition between rotational motions and bending costs, and we observe a surprising bias toward half-integer wave numbers. Their final hydrodynamic efficiencies are above 6%, significantly larger than those of swimming cells, therefore indicating available room for further biological tuning.
Some mechanistic requirements for major transitions.
Schuster, Peter
2016-08-19
reported here can be used to illustrate the interplay between competition and cooperation whereby we obtain a hint on the role that resources play in major transitions. Abundance of resources seems to be an indispensable prerequisite of radical innovation that apparently needs substantial investments. Economists often claim that scarcity is driving innovation. Our model sheds some light on this apparent contradiction. In a nutshell, the answer is: scarcity drives optimization and increase in efficiency but abundance is required for radical novelty and the development of new features.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431517
Nanoscale Thermotropic Phase Transitions Enhancing Photothermal Microscopy Signals.
Parra-Vasquez, A Nicholas G; Oudjedi, Laura; Cognet, Laurent; Lounis, Brahim
2012-05-17
The photothermal heterodyne imaging technique enables studies of individual weakly absorbing nano-objects in various environments. It uses a photoinduced change in the refractive index of the environment. Taking advantage of the dramatic index of refraction change occurring around a thermotropic liquid-crystalline phase transition, we demonstrate a 40-fold signal-to-noise ratio enhancement for gold nanoparticles imaged in 4-cyano-4'-pentylbiphenyl (5CB) liquid crystals over those in a water environment. We studied the photothermal signal as a function of probe laser polarization, heating power, and sample temperature quantifying the optimal enhancement. This study established photothermal microscopy as a valuable technique for inducing and/or detecting local phase transitions at the nanometer scales.
Phase transitions in crowd dynamics of resource allocation.
Ghosh, Asim; De Martino, Daniele; Chatterjee, Arnab; Marsili, Matteo; Chakrabarti, Bikas K
2012-02-01
We define and study a class of resource allocation processes where gN agents, by repeatedly visiting N resources, try to converge to an optimal configuration where each resource is occupied by at most one agent. The process exhibits a phase transition, as the density g of agents grows, from an absorbing to an active phase. In the latter, even if the number of resources is in principle enough for all agents (g<1), the system never settles to a frozen configuration. We recast these processes in terms of zero-range interacting particles, studying analytically the mean field dynamics and investigating numerically the phase transition in finite dimensions. We find a good agreement with the critical exponents of the stochastic fixed-energy sandpile. The lack of coordination in the active phase also leads to a nontrivial faster-is-slower effect.
Calculation of transition matrix elements by nonsingular orbital transformations
NASA Astrophysics Data System (ADS)
Kývala, Mojmír
A general strategy is described for the evaluation of transition matrix elements between pairs of full class CI wave functions built up from mutually nonorthogonal molecular orbitals. A new method is proposed for the counter-transformation of the linear expansion coefficients of a full CI wave function under a nonsingular transformation of the molecular-orbital basis. The method, which consists in a straightforward application of the Cauchy-Binet formula to the definition of a Slater determinant, is shown to be simple and suitable for efficient implementation on current high-performance computers. The new method appears mainly beneficial to the calculation of miscellaneous transition matrix elements among individually optimized CASSCF states and to the re-evaluation of the CASCI expansion coefficients in Slater-determinant bases formed from arbitrarily rotated (e.g., localized or, conversely, delocalized) active molecular orbitals.
Origami Optimization: Role of Symmetry in Accelerating Design
NASA Astrophysics Data System (ADS)
Buskohl, Philip; Fuchi, Kazuko; Bazzan, Giorgio; Durstock, Michael; Reich, Gregory; Joo, James; Vaia, Richard
Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. Design optimization tools have recently been developed to predict optimal fold patterns with mechanics-based metrics, such as the maximal energy storage, auxetic response and actuation. Origami actuator design problems possess inherent symmetries associated with the grid, mechanical boundary conditions and the objective function, which are often exploited to reduce the design space and computational cost of optimization. However, enforcing symmetry eliminates the prediction of potentially better performing asymmetric designs, which are more likely to exist given the discrete nature of fold line optimization. To better understand this effect, actuator design problems with different combinations of rotation and reflection symmetries were optimized while varying the number of folds allowed in the final design. In each case, the optimal origami patterns transitioned between symmetric and asymmetric solutions depended on the number of folds available for the design, with fewer symmetries present with more fold lines allowed. This study investigates the interplay of symmetry and discrete vs continuous optimization in origami actuators and provides insight into how the symmetries of the reference grid regulate the performance landscape. This work was supported by the Air Force Office of Scientific Research.
An optimal structural design algorithm using optimality criteria
NASA Technical Reports Server (NTRS)
Taylor, J. E.; Rossow, M. P.
1976-01-01
An algorithm for optimal design is given which incorporates several of the desirable features of both mathematical programming and optimality criteria, while avoiding some of the undesirable features. The algorithm proceeds by approaching the optimal solution through the solutions of an associated set of constrained optimal design problems. The solutions of the constrained problems are recognized at each stage through the application of optimality criteria based on energy concepts. Two examples are described in which the optimal member size and layout of a truss is predicted, given the joint locations and loads.
Effects of neuromuscular lags on controlling contact transitions
Venkadesan, Madhusudhan; Valero-Cuevas, Francisco J.
2009-01-01
We present a numerical exploration of contact transitions with the fingertip. When picking up objects our fingertips must make contact at specific locations, and—upon contact—maintain posture while producing well-directed force vectors. However, the joint torques for moving the fingertip towards a surface (τm) are different from those for producing static force vectors (τf). We previously described the neural control of such abrupt transitions in humans, and found that unavoidable errors arise because sensorimotor time delays and lags prevent an instantaneous switch between different torques. Here, we use numerical optimization on a finger model to reveal physical bounds for controlling such rapid contact transitions. Resembling human data, it is necessary to anticipatorily switch joint torques to τf at about 30 ms before contact to minimize the initial misdirection of the fingertip force vector. This anticipatory strategy arises in our deterministic model from neuromuscular lags, and not from optimizing for robustness to noise/uncertainties. Importantly, the optimal solution also leads to a trade-off between the speed of force magnitude increase versus the accuracy of initial force direction. This is an alternative to prevailing theories that propose multiplicative noise in muscles as the driver of speed–accuracy trade-offs. We instead find that the speed–accuracy trade-off arises solely from neuromuscular lags. Finally, because our model intentionally uses idealized assumptions, its agreement with human data suggests that the biological system is controlled in a way that approaches the physical boundaries of performance. PMID:19218157
Effects of neuromuscular lags on controlling contact transitions.
Venkadesan, Madhusudhan; Valero-Cuevas, Francisco J
2009-03-28
We present a numerical exploration of contact transitions with the fingertip. When picking up objects our fingertips must make contact at specific locations, and-upon contact-maintain posture while producing well-directed force vectors. However, the joint torques for moving the fingertip towards a surface (tau(m)) are different from those for producing static force vectors (tau(f)). We previously described the neural control of such abrupt transitions in humans, and found that unavoidable errors arise because sensorimotor time delays and lags prevent an instantaneous switch between different torques. Here, we use numerical optimization on a finger model to reveal physical bounds for controlling such rapid contact transitions. Resembling human data, it is necessary to anticipatorily switch joint torques to tau(f )at about 30 ms before contact to minimize the initial misdirection of the fingertip force vector. This anticipatory strategy arises in our deterministic model from neuromuscular lags, and not from optimizing for robustness to noise/uncertainties. Importantly, the optimal solution also leads to a trade-off between the speed of force magnitude increase versus the accuracy of initial force direction. This is an alternative to prevailing theories that propose multiplicative noise in muscles as the driver of speed-accuracy trade-offs. We instead find that the speed-accuracy trade-off arises solely from neuromuscular lags. Finally, because our model intentionally uses idealized assumptions, its agreement with human data suggests that the biological system is controlled in a way that approaches the physical boundaries of performance.
Electrical Conductivity in Transition Metals
ERIC Educational Resources Information Center
Talbot, Christopher; Vickneson, Kishanda
2013-01-01
The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…
Preterm Birth: Transition to Adulthood
ERIC Educational Resources Information Center
Allen, Marilee C.; Cristofalo, Elizabeth; Kim, Christina
2010-01-01
Preterm birth is associated with greater difficulty with transitions from childhood to adolescence to adulthood. Adolescents and young adults born preterm have higher rates of cerebral palsy, intellectual disability, cognitive impairment, learning disability, executive dysfunction, attention deficit disorder, and social-emotional difficulties than…
Leadership Transitions: Keys for Success
ERIC Educational Resources Information Center
Goodyear, Marilu; Golden, Cynthia
2008-01-01
A leadership transition poses dangers and challenges for both leaders and followers. While each party naturally focuses on the organization's success, time needs to be spent on how the new relationships will develop and mature into effective working relationships. This article discusses the following four areas of interaction between leaders and…
ROLE TRANSITION IN CAREER DEVELOPMENT.
ERIC Educational Resources Information Center
MOMENT, DAVID
ROLE TRANSITIONS IN ADULT CAREER DEVELOPMENT IS PRESENTED IN TERMS OF THE TECHNICAL, SOCIAL, AND DIRECTIVE ROLE ELEMENTS FOUND IN TWO STUDIES OF MANAGERIAL BEHAVIOR AND CAREER DEVELOPMENT. THE INDIVIDUAL'S LIFE SPACE IS THE BASIC FORMULATION OF THIS IDEA. THAT IS, MAJOR CHANGES IN THE CONFIGURATION OF THE INDIVIDUAL'S INTERPERSONAL NETWORK…
Supporting Student Veterans in Transition
ERIC Educational Resources Information Center
Rumann, Corey B.; Hamrick, Florence A.
2009-01-01
The purpose of this chapter is to offer frameworks and considerations for student affairs professionals seeking to serve the transition needs of the current generation of student veterans. The historical intersections of the military and higher education, particularly with respect to the effects of the draft on students and higher education,…
Narratives about Labour Market Transitions
ERIC Educational Resources Information Center
Cort, Pia; Thomsen, Rie
2014-01-01
In European Union policy, Denmark is often referred to as a model country in terms of its flexicurity model and provision of financial support and access to education and training during periods of unemployment, i.e. during transitional phases in a working life. However, in the research on flexicurity and its implications for labour market…
Gifted Students' Transition to University
ERIC Educational Resources Information Center
Mendaglio, Sal
2013-01-01
The transition from school to university presents novel demands for all students. Although this educational milestone has been addressed by scholars, particularly those interested in the study of higher education, there is a dearth of literature regarding gifted students' experience of their handling demands of first-year university. In the…
Structural transitions of encapsidated polyelectrolytes
NASA Astrophysics Data System (ADS)
Angelescu, D. G.; Linse, P.; Nguyen, T. T.; Bruinsma, R. F.
2008-03-01
Conformations and structural transitions of polyelectrolytes strictly confined onto a spherical 2D surface have been investigated by scaling descriptions based on physical arguments concerning polyelectrolyte adsorption onto planar surface and liquid crystals as well as by Monte Carlo simulations using a bead-spring model with short-range and electrostatic repulsions. In case of the electrostatic screened regime, a disordered-ordered (spiral) transition at increasing persistence length of the chain was found. It was predicted that the transition occurred when the persistence length is comparable with the mean spacing between adjacent strands of the ordered chain. The presence of a non-screened electrostatic repulsion led to a more complex behavior with i) a re-entrant order-disorder transition and ii) a tennis ball texture as an additional smectic/nematic structure. The various competing structures given by the theory were recovered by the Monte Carlo simulations, which also indicated that the tennis ball texture was favored over the spiral structure by the long-range interactions for semi-flexible chains.
Graczyk, Krzysztof M.
2011-11-23
A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-{Delta}(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.
Leadership Transitions during Fundraising Campaigns
ERIC Educational Resources Information Center
Nehls, Kimberly
2012-01-01
Capital campaigns are intense efforts to build the financial assets of an institution in a specified amount of time. This study provides an empirical view of how changes in leadership affected concomitant capital campaigns at ten colleges and universities. The transitions during these 10 campaigns influenced morale on campus, altered timing of the…
Postsecondary Transitions among Navajo Indians.
ERIC Educational Resources Information Center
Jackson, Aaron P.; Smith, Steven A.
2001-01-01
A study examining postsecondary transition experiences interviewed 22 Navajos who were recent high school graduates. Prominent themes included family influence and pressures, discrepancy between high school and college learning environments, student-faculty relationships, vague educational and career plans, misconceptions about postsecondary…
Transiting Exoplanet Survey Satellite (TESS)
NASA Technical Reports Server (NTRS)
Ricker, G. R.; Clampin, M.; Latham, D. W.; Seager, S.; Vanderspek, R. K.; Villasenor, J. S.; Winn, J. N.
2012-01-01
The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey, TESS will monitor more than 500,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat. A large fraction of TESS target stars will be 30-100 times brighter than those observed by Kepler satellite, and therefore TESS . planets will be far easier to characterize with follow-up observations. TESS will make it possible to study the masses, sizes, densities, orbits, and atmospheres of a large cohort of small planets, including a sample of rocky worlds in the habitable zones of their host stars. TESS will provide prime targets for observation with the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. TESS data will be released with minimal delay (no proprietary period), inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the very nearest and brightest main-sequence stars hosting transiting exoplanets, thus providing future observers with the most favorable targets for detailed investigations.
Transition metal sulfide loaded catalyst
Maroni, V.A.; Iton, L.E.; Pasterczyk, J.W.; Winterer, M.; Krause, T.R.
1994-04-26
A zeolite-based catalyst is described for activation and conversion of methane. A zeolite support includes a transition metal (Mo, Cr or W) sulfide disposed within the micropores of the zeolite. The catalyst allows activation and conversion of methane to C[sub 2]+ hydrocarbons in a reducing atmosphere, thereby avoiding formation of oxides of carbon.
Transition metal sulfide loaded catalyst
Maroni, Victor A.; Iton, Lennox E.; Pasterczyk, James W.; Winterer, Markus; Krause, Theodore R.
1994-01-01
A zeolite based catalyst for activation and conversion of methane. A zeolite support includes a transition metal (Mo, Cr or W) sulfide disposed within the micropores of the zeolite. The catalyst allows activation and conversion of methane to C.sub.2 + hydrocarbons in a reducing atmosphere, thereby avoiding formation of oxides of carbon.
On Comparing Transition Rate Gains.
ERIC Educational Resources Information Center
Reuterberg, Sven-Eric
This report is about the problem of making transition or enrollment rate gains comparable. It is shown that measures based on the proportions themselves, i.e. the difference between proportions, the proportion ratio and the residual gain ratio do not make the gains comparable. Instead a non-linear transformation has to be done. Two such…
"Mexico in Transition." Curriculum Units.
ERIC Educational Resources Information Center
Oregon Univ., Eugene. Foreign Language Resource Center.
These curriculum units were developed in a National Endowment for the Humanities 1994 summer seminar "Mexico in Transition." The 23 lessons are written in Spanish. Lessons are entitled: (1) "La Migracion Mexicana Vista a Traves del Cuento 'Paso del Norte' de Juan Rulfo" (Jose Jorge Armendariz); (2) "Los Grupos Indigenas de Mexico: Condiciones…